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Introduction

Environmental changes are natural and will continue to occur from time to time. Change can be abrupt or gradual, like climate change and global warming. Because of the changing environment, some creatures become extinct while certain species can thrive with very minor alterations. These modifications are passed down across generations, enabling the species to adapt to its environment and increase in population. These modifications are known as adaptations. A natural environment where a species grows and reproduces is known as a habitat.

Depending upon various habitats there are the following adaptations–

For more help, you can Refer to Lesson 9 – Living things and habitat in Science Class 6. Check out the video Lesson for a better understanding.

Adaptations in aquatic habitats

Numerous elements, such as light penetration, water composition (nutrient and salt content), oxygen availability, pressure, etc, are various factors that affect life in the aquatic environment. For these purposes, plants and animals are adapted in the following ways-

Plant adaptations-

• Aquatic plants have tissues called aerenchyma to move oxygen from exposed surfaces to low-oxygen submerged sections. 
• Aerenchyma also provides buoyancy to the plant and helps it float and helps to absorb natural light and oxygen.
• The root system is essentially nonexistent because water is all around them. If existent, it is rather small and mostly used for anchorage.
• To endure water currents leaves on submerged plants are typically tiny or ribbon-shaped.
• The stems are tall, hollow, light, and slender.
• Examples include water lilies, sea grass, and lotus.

Animal adaptations-

• Aquatic animals use their gills to breathe.
• Syphons are breathing tubes used by aquatic insects to draw oxygen from the air when submerged in the water. While some creatures, including salamanders, breathe through the skin.
• The blow holes on larger animals like whales and dolphins allow them to take in oxygen as they ascend to the surface and expel carbon dioxide.
• Fish have streamlined bodies to lessen swimming-related water resistance.
• Fins aid in swimming and tails act like rudders to maintain direction.
• Dolphins, whales, fish, etc. are a few examples.

Adaptations in desert habitat

Deserts are dry areas that only get a little rain occasionally throughout the year. It has an arid climate and rocky, sandy soils. Deserts face high temperatures and intense sunlight. For these purposes, plants and animals are adapted in the following ways-

Plant adaptations-

• A common desert adaptation is to conserve body fluids and prevent water loss through transpiration. To stop water loss through transpiration, desert plants’ leaves have thick, waxy cuticles.
• Due to the poor external availability, the stems are fleshy and store a lot of water.
• Desert plants have spines as a kind of defense against herbivores.
• To access deep subterranean water resources, plants have long, deep roots.
• Cacti, and agave, are some examples of desert plants.

Animal adaptations-

• The temperature in the desert is usually very high, hence small organisms have evolved nocturnal behaviors to ensure their survival. At night, when temperatures are generally low, they hunt for prey.
• Many desert animals have skin that is made to keep water from evaporating, and their bodies store lipids which can help them endure prolonged hunger periods.
• High-speed winds frequently carry small sand particles; these animals have large eyelashes, hairy ears, and tight nostrils which prevent sand from getting into their delicate bodily parts.
• Desert animals include kangaroo rats, camels, and desert cats.

Summary

Every living thing is constantly interacting with its environment. The percentage of survivors they have will determine how long the species will exist. Changes in the environment might be gradual or abrupt. However, organisms—whether they be plants or animals—develop specific inherited traits that enable them to adapt to environmental changes. We refer to them as adaptations. Desert-dwelling organisms have developed adaptations that reduce body water loss. Water-dwelling organisms have developed adaptations that help them breathe and adjust to the water pressure. Adaptations help organisms function better and are essential for survival.

Frequently Asked Questions

1. Give some common examples of adaptations.
Ans: Some examples of adaptations are- 

• Pointed teeth and claws of carnivores.
• Varied beak shapes to obtain food.
• Webbed feet of ducks.
• Leaves thick cuticles in xerophytic plants.
• White color fur in arctic animals prevents predation.
• Uricotelism in xerophytic animals.

2. What are Physical, physiological, and Behavioural adaptations?
Ans: Physical adaptations are characteristics that organisms have acquired as a result of their environment. To live in their ecological niche, organisms engage in internal functional mechanisms known as physiological adaptations. Behavioral adaptations are the behaviors or reactions the organism does in response to its surroundings.

3. Describe camouflage.
Ans: The physical adaptation of creatures to resemble or blend into their surroundings to survive attacks from predators is called camouflage.

Introduction:

Gypsum powder is called Plaster of Paris which is white. Gypsum is very common in Paris, which is how it earned its name. Gypsum is commonly heated to a higher temperature to make plaster of Paris. This is a dry powder that is mixed with water and hardens. When drying, this becomes flexible. In the field of architecture, plaster of Paris is used in a variety of ways. A famous substance, found in gauze bandages and sculpture materials is called the plaster of Paris.

Components of Plaster of Paris

Gypsum that has been roasted and milled into a fine powder is called plaster of Paris. Chemically it is written as\(\;CaS{O_4}.{\rm{ }}\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/\kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} {H_2}O\). Heat is generated as calcium sulfate transforms from its more soluble form\((CaS{O_4}.{\rm{ }}\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/\kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} {H_2}O)\) to its comparatively insoluble state\((CaS{O_4}.{\rm{ }}2{H_2}O)\) when water is added.

Properties of Plaster of Paris

1. POP is an ideal material for forming moulds because it doesn’t stretch or break when dried. Beautiful plasterworks, including cornices, are frequently constructed and maintained with this technique.
2. It is neither flammable nor combustible. It has a relatively weak chemical reactivity but, in extreme cases, can operate as an oxidizing agent. Hazardous sulfur oxides are produced during decomposition at moderately high temperatures. It creates gypsum \(CaS{O_4}\) by a slow and exothermic reaction with water or air moisture.

Washing Soda

Properties

A white, odorless dust is called washing soda. It has a chemical name termed sodium carbonate decahydrate, and its formula is\(\;N{a_2}C{O_3}.10{H_2}O\).

Its water-absorbing nature allows it to absorb moisture from the surrounding atmosphere. It is very soluble in water and creates a very basic solution.

Preparation

Through Solvay’s method, washing soda is produced. It starts as sodium bicarbonate, which is heated to become sodium carbonate. Finally, sodium carbonate is recrystallized to generate washing soda.

\[NaCl + N{H_3} + C{O_2} + {H_2}O{\rm{ }} \to {\rm{ }}NaHC{O_3} + N{H_4}Cl\]

\[2{\rm{ }}NaHC{O_3} \to N{a_2}C{O_3} + {H_2}O + C{O_2}\]

\[N{a_2}C{O_3} + 10{H_2}O \to {\rm{ }}N{a_2}C{O_3}.10{H_2}O\]

Baking Soda

Baking soda or bicarbonate of soda, also termed sodium bicarbonate,  is a chemical substance with the formula \(NaHC{O_3}\). Bicarbonate anion (\(HC{O_3}^ – \)) and the sodium cation (\(N{a^ + }\)) combine to form baking soda.

Properties

1. A white crystalline substance with a density of around 2.2 g/mL is known as sodium hydrogen carbonate. It tastes alkaline and is only slightly soluble in water. With an increase in temperature, sodium hydrogen carbonate becomes more soluble.
2. It is well known that baking soda can neutralize odors. Baking soda is therefore widely used to remove false odors from freezers and other closed spaces.

Preparation

In the reaction of a saturated sodium carbonate solution and carbon dioxide, sodium hydrogen carbonate (baking soda) is formed. Due to its low solubility, the white powder of sodium hydrogen carbonate isolates out.

Summary

Gypsum (calcium sulfate) powder and water are combined to create the plaster of Paris, which quickly dries. Medical professionals use plaster of paris to fix broken bones. Orthopedic casts still frequently utilize plaster of Paris. Washing soda’s pH is higher than that of baking soda. Baking soda, like the Arm & Hammer variety containing sodium bicarbonate, is edible and safe to use on human skin. It is not advisable to consume, breathe, or put alkaline washing soda on the skin.

Frequently Asked Question

1. How to make the plaster of Paris waterproof?

Ans: When the plaster of Paris is cured, it transforms into a highly porous material that will absorb any water that comes into contact with it. Plaster of Paris must have as many surface gaps as possible blocked to behave as waterproof for outdoors or brief exposure to water.

2. Is baking soda a blood pressure raiser?

Ans: Hypertension: Sodium bicarbonate may raise blood pressure. The use of sodium bicarbonate should be prohibited by individuals who already have high blood pressure. Low blood potassium levels: Sodium bicarbonate may decrease blood potassium levels.

3. What occurs if the plaster of Paris is left out in the open?

Ans: Plaster of Paris is a kind of rapid gypsum plaster that hardens when moistened and left to dry as it reacts with the moisture in the atmosphere to form gypsum. It is composed of a fine white powder termed calcium sulfate hemihydrate.

Introduction

O.Henry was the author of “The last leaf.” It tells the tale of a young girl who has pneumonia. Her name is Johnsy. All of Johnsy’s medications had ceased working on her because she had lost the desire to live. According to the doctors, she can only be healed if she is willing to live. Behrman resided in the same building and was an experienced painter. He was aiming to fulfill a lifetime ambition to create a painting that appeared to be real. He made an effort to assist Johnsy after learning about her situation.

Summary

“The Last Leaf” is a short story by O. Henry about two young artists, Johnsy and Sue, living together in a Greenwich Village apartment. It is a tale of inspiration and sincere dedication. Johnsy is the story’s main protagonist. She is a young girl who has pneumonia and is suffering severely. She no longer has the desire to live, and thus, the medications stopped curing her. Sue was informed by the doctor that only her willingness to live could rescue her. Sue shared the same with Behrman, a painter who lived next door.

Johnsy once saw an ivy plant through the window as she was resting in bed. It was progressively losing all of its leaves. Johnsy saw the state of the tree and predicted that she would pass away the day the last leaf fell from the tree. The plant had nothing to do with her sickness still Johnsy decided to say that.

Because Sue was so concerned about Johnsy’s choice, she got in touch with Behrman and told him about Johnsy’s decision. Behram closed the window after seeing the plant from Johnsy’s room. That entire day it rained too much along with the storm, and she sensed that the ivy plant’s leaves would soon shed. She hesitantly peered out the window and noticed that the creeper just had one leaf left, which might come off at any moment. Behrman remained silent, though, and went back to his room. The old artist made a decision that evening to help Johnsy. While Johnsy was sleeping, he painted a leaf from an ivy plant and tied it to the creeper.

The leaf remained still attached to the ivy plant the following day when Johnsy looked out the window. She thought that despite the torrential rain and storm the leaf still clung to the creeper and this provided her the inspiration she needed to live. She felt that she should adopt the same outlook, keep trying to improve, and not give up on herself.

Behrman spent the entire night working on that painting before hanging it from a tree in the middle of a chilly, rainy night. Behram also had pneumonia, and unfortunately, he passed away after two days. He had made the ultimate sacrifice to save Johnsy’s life. She found hope for survival in the last leaf on the Ivy plant.

Johnsy learned that it was silly of her to decide her entire life on the last leaf of a plant. She realized that the last leaf in the creeper must have been there for a significant reason, and she understood that it was terrible for her to wish to die so soon. Johnsy quickly recovered from her ailment.

Sue told Johnsy of Behrman’s demise after she had fully recovered from pneumonia. He died of pneumonia and he had contracted the illness while staying outside in the chilly, rainy weather. She also informed Johnsy that he had painted the last leaf to offer Johnsy hope for surviving. Finally, Behrman had completed his masterwork, the last leaf that gave Johnsy hope for a longer life while he sacrificed his own life in the process.

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The Last Leaf Characters

Character Sketch of Sue

Sue is Johnsy’s best friend and roommate. She is a practical and caring person who tries to lift Johnsy’s spirits and help her recover from her illness. Sue is depicted as a compassionate and selfless character who is willing to sacrifice her own needs to help Johnsy.

Character Sketch of Johnsy

Johnsy is a young artist who is ill with pneumonia and has lost her will to live. Johnsy’s real name was Joanna. She is a dreamer and often spends time looking out the window at the ivy vine. She believes that when the last leaf falls from the vine, she will die. Her character is depicted as weak and fragile, with a tendency to give up easily. However, she is also shown to have a deep sensitivity and appreciation for art.

Character Sketch of Behrman

Behrman is an old painter who lives on the ground floor of Johnsy and Sue’s building. He is a bohemian character, and his life is centered around his art. Behrman is depicted as a gruff and eccentric character with a grumpy demeanor, but he also has a kind and compassionate side. He is determined to protect the young artists and is willing to take risks to do so.

Character Sketch of Doctor

The doctor is a minor character in the story who is called to attend to Johnsy. He is depicted as a professional and competent medical practitioner who is determined to help his patient recover. He is also shown to have a compassionate and caring side, as he understands Johnsy’s fear of death and tries to reassure her.

Conclusion

The protagonist of the tale is a young child who is hopelessly miserable. She made the absurd claim that she would pass away when the Ivy plant sheds all its leaves. A painted leaf that appeared to be real was hanging on the tree made by an old painter named Behrman. The child was, motivated to live when she saw the leaf clinging to the ivy plant despite the storm and rain. Thus, she recovered from the disease and lived a happy life.

TextBook Question

Q.1 What is Johnsy’s illness? What can cure her, the medicine or the willingness to live?

Ans: Johnsy suffered from pneumonia. Her health cannot be cured by medicine alone, her willingness to survive is the main cure.

Q2. Do you believe that Johnsy’s experience of depression is typical of teenagers?

Ans: Yes, I believe that Johnsy’s sadness is rather typical for teenagers today. Teenagers today are constantly striving to improve their life. They have a life where there is constant pressure to excel in every way.

Q3. What is Behrmans dream? Does it come true?

Ans: Behrman’s ultimate goal was to create a masterpiece that looked very real. It eventually becomes true as he paints the last leaf on an ivy creeper and it appears to look like a real leaf.

Q4. What is Behrman’s masterpiece? What makes Sue say so?

Ans: The last leaf on the creeper was Behram’s masterpiece. Sue makes this claim because Behram changed the original leaf secretly in his picture, making it appear real and motivated Johnsy to live.

The Last Leaf Extra Questions

1. What message does the final leaf convey?
Ans: The story’s overarching theme is hope. The author wants to emphasize how crucial it is for a person to have hope and willpower. When Johnsy notices that the leaf that is meant to determine her fate is not falling, she is given new hope. This demonstrates how a person’s hope can be lit by even a tiny deed.

2. What is the offering on the Last leaf?
Ans: Behrman sacrifices his LIFE in “The Last Leaf” so that Johnsy can recover from pneumonia.

3.What did Sue and Johnsy argue about in The Last Leaf?
Ans: Sue and Johnsy argue over Johnsy’s habit of staring out the window at the vine as it sheds its leaves. Johnsy is waiting for the last leaf to fall so that she can pass away, despite Sue’s requests for her to look aside from the wall.

Introduction

The sacrifice of a prince and a bird is the main element of the Happy Prince. The narrative accurately portrays a prince who cares for his subjects. The prince in the story was always joyful because he never saw sadness or misery around him. When the prince passes away, a statue of him was built on a height. His eyes were made of sapphires, and the statue was constructed of gold. With all of his wealth, the prince was no longer content because he had witnessed the pain and agony of his people, and he now works to make everyone happy and assist the less privileged.

Summary

It is a story about the statue of a happy prince. A bird once sought refuge beneath the statue of Happy Prince. When the bird noticed that the prince was not content, she inquired as to why. The prince then retorted that he was known as the happy prince since he never experienced sadness or misery during his lifetime. However, after he passed away and his statue was built outside the castle, he now senses the sufferings of his unfortunate subjects.

The bird made the decision to be the messenger of the prince and aid the less fortunate. The prince instructed him to give the seamstress the ruby from his sword so she could treat his sick son. Then he requested that the Bird offer his one sapphire eye to an artist who was unable to write his play because he was cold and hungry.

One day, he witnessed a match girl being hit physically by her father after she accidentally dropped matches in the canal. He instructed the bird to remove his other eye and offer the sapphire to that young lady. Post this the prince was totally blind, thus, the bird made the decision not to go anywhere but stay with the prince and serve the underprivileged.

The prince lost his sight yet continued to aid the needy. Following the prince’s orders, the Bird dutifully removed the golden leaves from the monument and continued to assist the underprivileged. The statue lost its luster as the poor received all of its gold and sapphires. Then a long winter arrived, which ultimately took the life of the swallow bird, it fell close to the monument. The prince’s leaden heart split in half upon seeing this. As time passes the statue looked dull and unattractive and thus the municipal council members agreed to destroy the statue and melt it in the furnace. The whole statue got destroyed but the heart remained the same which was also thrown near the dead swallow.

God sent an angel to earth and instructed him to collect the most priceless items from the earth; upon his return, the angel carried the prince’s heart and the swallow’s body. Both of them were welcomed by God in his garden.

Textbook Question Answers

1. Why do the prince’s courtiers refer to him as “the Happy Prince”? Is he actually content? What is it that he notices everywhere?

Ans: The prince was known as “The Happy Prince” by his courtiers because, while he was alive, he never experienced sadness. He was actually no longer content because, as a statue raised to a height, he could observe the anguish, misery, and ugliness of his land.

2. Why does the Happy Prince send the seamstress a ruby? What is the role of the swallow in the seamstress’ home?

Ans: Because she was in need and his only son had a fever, the prince sent a ruby to the seamstress. The swallow treated his son at the seamstress’ home.

3. To whom and why does the prince send the sapphires?

Ans: The young writer and the match girl receive the sapphires from the prince, respectively. In order to help the young author finish his play after he fainted from hunger and cold, the prince sends him a sapphire. The match girl dropped matchsticks in the gutter by mistake and his father was beating her. In order to help each of them with their issues, the prince sends sapphire.

4. the swallow flies over the city, what does it see?

Ans: The swallow observes the stark disparity between the lifestyles of the rich and the poor as it hovers over the city. He witnesses wealthy people getting married in their lavish homes while beggars wait outside the gates.

5. Why did the swallow not leave the prince and go to Egypt?

Ans: The swallow was moved by the prince’s kindness, so he chose not to leave him and travel to Egypt.

6. What are the priceless items described in the story? Why are they valuable?

Ans: The leaden heart of the prince and the bird were the two most valuable items in the tale. The bird abandoned his desire to travel to Egypt and chose to live with the prince in order to aid the needy while the prince gave away all of his treasures, including his sapphire and gold.

Extra Questions

1. What is the moral of the story The Happy Prince?

Ans: The story’s message is that we should assist the less fortunate and those in need. The happy prince was an example of this as he gave his diamonds to the underprivileged and needy. The swallow proved to be a wonderful symbol of love and selflessness. Acts of kindness and generosity can have a profound impact on others, and even inanimate objects can possess human qualities. The story emphasizes the need for empathy and a willingness to help those less fortunate.

2. What qualities does the Happy Prince possess?

Ans: The Prince is described as having golden skin, sapphire eyes, and a ruby on the hilt of his sword. Although he is physically attractive to many around him, he believes that this beauty is simply surface-level. He believes that his genuine beauty rests in his compassion for his town’s people and his readiness to make sacrifices for them.

3. What represents Happy Prince?

Ans: The Lead Heart is the symbol that signifies The happy prince. The Happy Prince’s heart is made of lead, and when his beloved Swallow dies from the cold, it breaks.

Introduction

Have you ever questioned why straw that has been dipped in water appears warped? When the water is added to the glass, the straw appears to bend, but when you remove it, you can see that it hasn’t actually bent at all. Refraction is to blame for this; rather than the straw itself, it bends the light around it. Likewise occurs when a pencil is inserted into a glass of only partially full water. If you look at the pencil, you can see that it looks normal above the water but twisted and a little bigger below. There are numerous such instances of refraction in daily life that will be covered in this chapter.

Refractive index of light

The refractive index of any material is given as the ratio of the speed of light in the vacuum divided (c) by the speed of light in a medium (v), and is presented with a symbol, n, such that,

$$
n=\frac{c}{v}
$$

We can infer from this relationship that optical density and light speed both affect the refractive index. With an increase in optical density, the refractive index often rises. Light may bend more when it enters a denser material than when it enters a rarer one. Additionally, as the medium’s medium’s light speed decreases, the refractive index rises.

Prism

A transparent substance that can reflect light and has at least two lateral surfaces that are obliquely inclined to one another is referred to as a prism. It contains five surfaces, including three rectangle lateral surfaces and two triangle bases. The angle of the prism refers to the angle created by two lateral surfaces. For a standard prism, the prism’s angle is always 60°.

Refraction of light through a prism

A light ray NP is seen entering glass at the initial surface OB in the diagram as it travels from air. Because glass is denser than air, incoming light is bent toward the normal after refraction. When light enters from glass into air at the second surface BC, it bends away from the usual. A line drawn perpendicular to the surface at the incident ray entry point is called a normal. In contrast to angle of emergence, which is the angle produced between the emergent ray and the normal, angle of incidence is the angle formed between the incident ray and the normal. The angle that the emergent ray (stretched rearward) creates with the incident light is known as the angle of deviation ($\angle D$) (extended forward). The equation can be written from angle of prism (∠A), angle of incidence (∠i) and angle of emergence (∠e). Therefore, the expression is given as,

$$
\angle D=\angle i+\angle e-\angle A
$$

Refractive index of a prism

Refractive index of a prism made up of glass is given by the formula,

$$
n=\frac{\sin \frac{(A+D)}{2}}{\sin \left(\frac{A}{2}\right)}
$$

Where n is the refractive index of the prism, A is the angle of the prism and D is the deviation. The deviation is minimum at one point and is called minimum deviation. Using this formula, we can easily calculate the refractive index of the prism.

Angle of deviation

It refers to the angle at which the emergent ray and incident ray make contact. Angle of deviation is affected by a variety of factors.

Refractive index

The refractive index is directly proportional to the angle of deviation. 

Angle of prism 

The magnitude of the angle of deviation increases with an increase in the angle of the prism.

Wavelength of light

As the wavelength increases, the angle of deviation decreases. Therefore, violet deviates the most, because it has a shorter wavelength.

Temperature

As temperature increases, intermolecular space also increases, density decreases, refractive index decreases and angle of deviation decreases. 

Dispersion of light through prism

The white light, composed of the whole spectrum) is divided further into its components called the spectrum when it passes through a prism. This phenomenon is called  The white light divides into its seven individual colours. These hues are a part of VIBGYOR (V-violet, I- indigo, B-blue, G-green, Y-yellow, O-orange, R-red). The wavelengths of these hues determine their deviation. Red has the longest wavelength among these colours, whereas violet has the shortest. As we previously established, the angle of departure increases with decreasing wavelength. Due to the fact that light propagates at different speeds, it “bends” or is “refracted” when it travels through a medium. At this point, light passing through a prism is deflected in the direction of the triangle’s base. Each of the many colours that make up light has a unique wavelength. Because of this, each of them bends at a different rate depending on its wavelength, with violet bending at the fastest rate because it has the shortest wavelength and red bending at the slowest rate because it has the longest. As a result, the spectrum of colours in white light are separated into their individual colours when it is refracted via a prism.

Summary

Refraction, which is the bending of light as it travels through two distinct media, has a variety of uses. Light slows down and bends when it passes through a prism. The pool appears to be shallower than it actually is. This results from the way light beams from the water’s bottom curve when they exit the water and enter the atmosphere. Have you ever noticed the water layer forming over a short distance in a desert or on a road on a sunny day? “Mirage” is the name given to this occurrence.

Frequently asked questions

1. Why do stars twinkle in the night sky?

Ans: A significant factor in this phenomenon is atmospheric refraction. The refraction of light caused by the earth’s atmosphere, which is made up of air layers with various optical densities, is referred to as “atmospheric refraction.” Light beams from stars are constantly changing their direction as they pass through the earth’s atmosphere due to the changing optical density of the atmosphere. It might affect the amount of starlight that reaches our eyes. The stars in the night sky appear to twinkle as a result.

2. How many refraction patterns are possible for a light beam when it passes through a prism? Explain.

Ans: The speed of the beam may decrease as it passes through air toward a prism, finally slowing down and bending. It also experiences additional refraction as it passes through the prism. Snell’s law of refraction allows us to draw this conclusion. This law states that a light beam moving from a rarer to a denser material may slant in the direction of normal. In a similar way, light beams can stray from the usual when they move from a denser to a rarer medium. As a result, there are two possible refractions.

3. Identify the graph and predict which colour of VIBGYOR has the minimum deviation.

Ans: This is a plot along the X and Y axes against the angle of incidence and the angle of deviation (a). This graph shows how a light beam deviates when it passes through a glass prism. White light splits up into its individual colours when it enters the prism. The wavelength of the light coming in determines how far the deviation extends. Light deviates the least and has the highest wavelength. Red has the highest wavelength among VIBGYOR. Red therefore deviates the least from the norm.

 

Introduction

Following the French Revolution, France’s political system changed from an absolute monarchy to a democratic republic. The establishment of the National Assembly, the Reign of Terror, and Directory rule all occurred during France’s republican period. September 1792 saw the founding of the first republic, France. This First Republic persisted until May 1804, when Napoleon Bonaparte ushered in the First Empire or Napoleonic France. After the declaration of the revolution, from 1792 until the present, France had five republics.

How France Became a republic

The anger against the Ancient Regime in French society grew when King Louis XVI assumed power, laying the groundwork for the French Revolution. The National Convention created a new constitution in 1791 as a result of this uprising, which limited the king’s authority by establishing a constitutional monarchy and securing citizens’ basic rights. With the monarch’s abdication in 1792, this constitutional monarchy likewise came to an end. After that, in 1792, the newly elected members of the National Assembly unanimously proclaimed France to be a republic, which led to the establishment of the French Republic.

The Jacobins took advantage of the political unrest to grab control of the National Convention, ushering in a period of terror that saw widespread killing and bloodshed throughout France. With the middle class seizing control and establishing the Directory government in France, this situation and the Jacobin republic came to an end in 1794. However, there were numerous disputes even during the directory rule, which led to the establishment of the French Consulate under the leadership of Napoleon Bonaparte as the First Consul. Napoleon later proclaimed himself the Emperor of France and ended the First French Republic to establish the First Empire.

Helping Factors

The despotic, autocratic monarchs were overthrown by the French Revolution, which also created new political and social structures based on the ideals of liberty, equality, and fraternity. The new form of governance was the democratic republic. The conditions were right for France to become a republic for several causes, and things happened:

• Replacement of the absolute monarchy with the Constitutional monarchy 
• End of the monarchy and the formation of the National Convention 
• Reign of Terror 
• Directory Rule

Replacement of the absolute monarchy with the Constitutional monarchy

The king’s concentrated power was reduced after the Revolution. In the new constitution that the National Assembly drafted in 1791, the parliament served as a check on the king’s authority. The legislative, the executive branch, and the judiciary now shared power. This system of government was known as a Constitutional monarchy.

End of the monarchy and the formation of the National Convention

Even though he ratified the constitution, King Louis XVI was not pleased with the reduction of his authority. He, therefore, began secret negotiations with world leaders who were likewise concerned about the progression of the French Revolution. As a result, the neighbouring nations of Austria and Prussia consented to assist him in putting down the uprising. In 1792, the National Assembly declared war on these nations after learning of King Louis’ and his allies’ plans.

The French revolutionaries recruited volunteers from many provinces to fight for the creation of popular supremacy by overthrowing the king and nobles. Massive destruction was caused by these revolutionary battles, especially for the common people. The Jacobins’ siege on the Tuileries Palace in 1792 resulted in the capture of King Louis XVI and Marie Antoinette. On September 21, 1792, they held elections to choose the members of the new assembly, which became known as the National Convention. The constitutional monarchy came to an end as a result of this event, and France became a republic. The monarch and queen were later put to death in 1793.

Reign of Terror

The Jacobins took over as the dominant group when France was declared a republic. Maximilien Robespierre, the leader of this group, oversaw the harsh punishments and rule that began the reign of terror in France in the years 1793–1794. During this time, those who were thought to be republican and revolutionary foes were put to death. To maintain the Jacobins’ hegemony, he outlawed other political organizations. The “enemy” was beheaded using a contraption called a “guillotine.” The French people began to rebel against Robespierre’s rule as the leader of the Jacobin Club, which led to his execution.

Directory Rule

The more affluent middle class once again came into power when the Jacobin regime was overthrown. They drafted a new constitution, in which they once again restricted voting to members of the affluent class. This resulted in the establishment of two legislative councils. In addition, they established a Directory, a five-person executive body, to make decisions rather than consolidating authority in the hands of a single executive like the Jacobins. However, this division of authority among various organizations and departments led to regular disputes between the legislature and the directory.

Summary

Following the French Revolution, France had to undergo several political structure changes, including the overthrow of the absolute monarchy, initially led by King Louis XVI, the emergence of the constitutional monarchy, the Jacobin government, the Directory rule, and the ascension of Napoleon Bonaparte to the position of Emperor. The nobility lost its rights, and the society’s feudal framework was abolished.

Frequently Asked Questions

1. What does ‘Republic’ mean?
Ans. “Republic” describes a state in which its residents directly or indirectly elect the state’s leader. The position of the head is also not inherited.

2. Why were people dissatisfied with the rule of King Louis XVI?
Ans. People were unsatisfied for numerous reasons during the reign of King Louis XVI: Since Louis XVI’s reign, France has spent a lot of money fighting wars in Europe. The royal treasury was burdened by the king’s extravagant lifestyle. The king had unchecked power and was not answerable to the people. The king increased taxes on the Third Estate because the economy was close to collapse.

3. Where was King Louis XVI executed?
Ans. King Louis XVI is put to death by guillotine in Paris’ Place de la Revolution, one day after the French National Convention found him guilty of conspiring with foreign powers and sentenced him to death.

Introduction

An atom’s energy changes due to electron affinity. A neutral atom gains energy and a negative charge when electrons are added to its outer shell. To stabilise its octet, an element gains electrons. When an element accepts or loses an electron, energy is released. When an element accepts an electron to form a compound, it releases energy, which is referred to as an exothermic reaction. The energy is released in an exothermic reaction in order to attract the electron by a nucleus from another element. When an element loses an electron, it absorbs energy, a process known as endothermic. An atom gains energy when it loses electrons.

What do you mean by Electron Affinity?

When atoms accept electrons, they emit energy, which is referred to as an exothermic reaction. Atoms that lose an electron in a chemical reaction, on the other hand, absorb energy and are known as endothermic reactions. The ability to accept an electron is referred to as electron affinity. When a neutral gaseous atom accepts an electron, it gains a negative ion charge. The first electron affinity is always negative, while the second is always positive. It is difficult to measure the electron affinity of an atom. It is determined by the energy released by ionic compounds. The electron affinity is also measured by an atom’s tendency to act as an oxidising or reducing agent. It is measured in kilojoules/moles. Electron affinity is symbolised by EA.

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Factors Influencing Electron Affinity

The atomic size of the element, the nuclear charge on the molecules, and the electronic configuration of atoms are all factors that influence a molecule’s electron affinity.

1. Atomic size: Atoms with smaller sizes have greater electron affinity than atoms with larger sizes. The nucleus of smaller atoms is more attractive to electrons than the nucleus of larger atoms. As the atom’s size increases, the outer shell becomes further away from the nucleus, and the attraction for electrons in the outer shell decreases. 
2. Nuclear Charge: The nuclear charge influences electron affinity as well. As the charge on an atom increases, so does the attraction in electrons, and thus the electron affinity. When a molecule is already charged, electron repulsion increases, and the pull from the nucleus increases, resulting in increased electron affinity in charged ions.
3. Shielding Effect: As the screening effect on an atom’s inner shell is reduced, the electron affinity increases.
4. Electronic Configuration: The electronic configuration also affects electron affinity. Because elements with full octets have zero tendencies to accept electrons, electron affinity in inert gases is zero. The electronic configuration is crucial in electron affinity. Metals have a lower affinity for electrons than non-metals due to their electronic configuration.

Summary

The ability to accept electrons in gaseous form and form an anion is referred to as electron affinity. The process of accepting electrons generates energy, which is why it is referred to as an exothermic process. When we move from group to group, the electron affinity decreases and increases when we move from period to period. It is denoted by the symbol EA and measured in Kilojoules per Mole (KJ/Mol). Because of electron-electron repulsion, the first electron affinity is always less than the second electron affinity. The atomic size, electronic configuration, screening effect, and nuclear charge of elements all influence electron affinity.

Frequently Asked Questions

1. Why do noble gases have no electron affinity?

Ans. Noble gases have zero electron affinity because their octet is complete, and they do not have an affinity for electrons. As a result, noble gases have no electron affinity.

2. Why does group 17 have such a strong electron affinity?

Ans. Because the halogens are small and have more electrons in the outer shell, the elements of the halogens group have a high electron affinity. A halogen would rather accept an electron than lose seven electrons to complete its octet.

3. Why does fluorine have a lower electron affinity than chlorine?

Ans. Because the atomic size of fluorine molecules is smaller than that of chlorine molecules, the outer shell of fluorine is already filled with electrons, and the nucleus is much closer to the outer shell, the electron repulsion is greater than the force of attraction of the nucleus when an electron is placed in the outer shell of fluorine molecules compared to chlorine molecules.

Introduction

How does a mobile phone’s battery charge when plugged into its charger, or how does the cell in a TV remote control work? All of these questions have answers in the scientific field of electrochemistry. Electrochemistry is the study of both the use of electricity to conduct non-spontaneous chemical reactions and the production of electricity through chemical reactions. To achieve the goal, cells are used. Cells are components that initiate chemical reactions that produce or generate electricity.

What is an electrochemical reaction?

An electrochemical reaction is any process that is initiated or accompanied by the flow of electrical current, and typically involves the transport of electrons between two substances—one solid and one liquid. An electrochemical reaction occurs when a solid electrode and a material, such as an electrolyte, interact. This flow causes the reaction to release or absorb heat by producing an electric current to pass across the electrodes. When, for example, two electrodes in contact with one another initiate an oxidation and reduction (redox) reaction, the oxidation number of all the atoms involved in the reaction changes.

The process of electrochemical reaction

The properties of the negatively charged\(\;{e^ – }\)determine how matter interacts with an electric current as it flows through a system. Because protons are positively charged matter units found in elements, groups of atoms, or molecules, the electron, the fundamental unit of electricity, is drawn to them. This attraction is comparable to the chemical attraction that particles have for one another. Every chemical reaction changes the structure of an atom’s electrons, and the liberated electrons can either join with matter particles to form reductions or be ejected by them (oxidation). 

Faraday’s rules define the quantitative relationship between a free electron in a current flow and the atoms of a substance, where they cause a reaction. Electrochemical process components are also known as ionic conductors or electrolytes.

What is an Electrochemical cell?

An electrochemical cell is a system that can generate electrical energy from spontaneous chemical reactions. The chemical processes that occur during this process are known as redox reactions. During redox reactions, electrons are transferred between chemical species. They are also referred to as galvanic or voltaic cells. An electrochemical cell is illustrated by the Daniell cell.

The following are the essential components of an electrochemical cell:

1. An electrolyte is a substance found between electrodes that, when dissolved in polar solvents such as water, produces freely flowing ions, resulting in an electrically conducting solution.
2. Electrodes are solid electrical conductors that are used in electrochemical cells and are made of good conductors, such as metals.
3. They are available in two varieties:
4. The Cathode is the area of the cell where reduction takes place.
5. The anode is the part of the cell where oxidation takes place.
6. A salt bridge connects the oxidation and reduction halves of an electrochemical cell, completing the circuit. It is brimming with KCl and other saturated salt solutions. The bridge is required for the ions in the solution to flow between half-cells.

What are the different kinds of electrochemical cells?

There are two major kinds:

1. Galvanic Cell / Voltaic Cell: Chemical energy is converted to electrical energy in these electrochemical cells.
2. Electrolytic Cell: In these cells, electrical energy is converted to chemical energy.

Explain its operation

• Working Principle

The fundamental operating principle of an electrochemical system is the transfer of\(\;{e^ – }\)produced by a redox reaction occurring in it, which results in an electric current.

• Working Mechanism 

When the switch is turned on after an electrochemical cell has been fully assembled, the galvanometer of the external circuit deflects. The needle of the galvanometer moves in the direction of the beaker containing the copper sulphate solution. It indicates that the current has changed direction from the copper sulphate solution beaker to the zinc sulphate solution beaker. When the circuit is completed, a change occurs that causes zinc atoms in the zinc electrode to oxidise and Cu atoms in the copper rod to reduce. Zinc releases two electrons, which copper accepts via an external circuit.

Full redox reaction: \(\;Zn{\rm{ }}\left( s \right){\rm{ }} + {\rm{ }}C{u^{2 + }}\left( {aq} \right){\rm{ }} \to {\rm{ }}Z{n^{2 + }}\left( {aq} \right) + Cu{\rm{ }}\left( s \right)\;\;\;\)

Some applications of Electrochemical Cell

1. Many non-ferrous metals are electro-refined in metallurgy using electrolytic cells, yielding very pure metals such as Pb, Zn, Al, and Cu. 
2. It is used to recover pure Na metal from molten NaCl by storing it in an electrolytic cell.
3. Silver oxide batteries are used in hearing aids.
4. Thermal batteries are used in Navy gadgets for military applications.

Applications of Electrochemistry

1. Electrical batteries are created using the concept of cells. A battery is a device used in science and technology that stores chemical energy and provides electrical access to it.
   1. Applications in defence (thermal batteries)
   2. Digital cameras (Li batteries)
   3. Audio equipment (silver-oxide batteries)
2. Electroplating is used for a variety of purposes, including the production of jewellery and the corrosion protection of certain metals.
3. Electrochemistry is required in a variety of industries, including the chlor alkali industry.

Summary

Electrochemistry is a fascinating subject. Electrochemical reactions are important to comprehend because they have significant academic and practical implications. Understanding the responses allows us to better understand how everyday objects such as a battery or cell work. Chemical energy can be used to generate electrical energy in electrochemical cells, and electrical energy can be used to generate chemical energy.

Frequently Asked Questions 

1. What factors affect electrode potential?

Ans. The reduction potential refers to an electrode’s ability to accept electrons, whereas the oxidation potential refers to an electrode’s tendency to lose electrons. The potential of an electrode is determined by the temperature and metal ion concentration at its surface.

2. Can a zinc pot be used to store copper sulphate solution?

Ans. Copper has a lower reactivity than zinc. As a result, zinc can remove Cu from its salt solution. If the\(\;CuS{O_4}\) solution is kept in a zinc container, copper will be removed from the solution.

\[Zn + CuS{O_4} \to ZnS{O_4} + Cu\]

As a result, the copper sulphate solution cannot be stored in a zinc pot.

3. In the SI system, what is the emf measurement?

Ans. The energy contained in a battery per Coulomb of charge is known as the electromotive force, EMF has a SI unit of volts, which is equal to joules per coulomb.

Introduction

In the Mughal empire, the Maratha union was one of the most formidable kingdoms. Between 1674 and 1818, the Marathas ruled. During this period, they controlled the Deccan region of India. During the eighteenth century, they posed a serious threat to the Mughals and the British Empire.  Guerilla warfare was well mastered by these Marathas. The Maratha confederacy was divided into different states under different chieftains such as Gaikwad, Sindhias, Holkars, and Bhonsle’s. Bhonsle was a powerful clan in Maratha, and Shahji and Shivaji were two of its important warriors.

The Maratha empire

The Bhonsle chief Shivaji laid the foundation for the Maratha empire. Before him, the Marathas were scattered among many confederacies in Deccan. He thus unified all the confederacies and gave them a hard time to the Mughals. The Marathas expanded from the Deccan to northern India after Mughal rule ended, leading to the establishment of the Maratha Empire. In 1761, Ahmad Shah Abdali challenged Maratha’s authority at the Third Battle of Panipat to determine who would inherit the Mughal dominion.

Other than the weak and waning Mughal rule, other factors that contributed to the rise of the Marathas included: the Maratha nationalism fostered by Bhakti movement leaders like Tukaram, Eknath, and Ramdas; their geographic location, which gave them access to ready-made rock forts to govern their kingdoms; and the political unrest in the south.

Who ruled the Maratha Kingdom?

The Maratha empire was divided into five confederacies; Peshwas of Pune, the Gaekwads of Baroda, the Bhonsles of Nagpur, the Holkars of Indore, and the Scindhias of Gwalior. Shivaji brought together all of these confederacies under the Maratha Empire. Under his leadership, the Marathas were always a political threat to the Mughals and the British. Maratha power passed to Sambhaji after Shivaji died. He was also among the strongest warriors, never losing a battle to the Mughals. Aurangzeb executed him in the end. A civil war broke out between Shahu and Tarabai after Sambhaji.

Shahu ascended to the kingdom with the aid of Balaji Vishwanath, and in exchange, he named Balaji Vishwanath Peshwa or Chief Minister. Because Shahu was a weak leader, Peshwa gradually began to gain control of the realm. The first Peshwa who established Maratha dominance was Balaji Vishwanath.

 What was the title of Shivaji?

In 1674, the Maratha warrior Shivaji received the honorific title “Chhatrapati.” The Sanskrit name Chhatrapati was employed by the Marathas to designate a ruler. The word chatra in this title alludes to the top of an umbrella, and pati denotes the owner or master. Therefore, the term “Chatrapati” refers to a particular type of ruler who served as an umbrella to cover and secure his subjects. Shivaji used this title because it indicated a monarch who was also a protector, as opposed to the titles Raja or Maharaja, which only indicate a ruler.

Maratha empire during Peshwas Era

Territories that were formerly a part of Shivaji’s empire but had been seized by Aurangzeb were returned by Balaji Viswanath, the first Peshwa of Shahus. He also assisted the Sayyid brothers in deposing Farrukhsiyar, the Mughal emperor. Six Mughal provinces in the Deccan received the Sardeshmukhi and Chauth taxes from him. His son Baji RaoI succeeded him as Peshwa. The Maratha kingdom became an empire during his rule. He also overcame Nizam-ul-Mulk and signed the Durai Sarai pact, which gave him control of Malwa and Bundelkhand.

Balaji Baji Rao, commonly known as Nana Saheb, succeeded his father, Baji Rao I, as Peshwa. He extended Maratha territory into Punjab and Delhi. The Marathas’ conquest of Punjab also brought them into conflict with Ahmed Shah Abdali, and in the Third Battle of Panipat, which took place in 1761, the Marathas suffered a crushing defeat that resulted in the deaths of several Maratha leaders, roughly 28,000 soldiers, and Vishwas Rao and Sadashiv Rao Bhau.

The Decline of Martha’s empire

The subsidiary alliance signed by Baji Rao II at the tail end of the 18th century and the beginning of the first quarter of the 19th century marked the beginning of the Maratha kingdom’s decline. The decline of the Marathas was caused by several factors, including the following:

• Internal strife among Maratha chiefs from various confederacies jeopardized the empire’s unity. British people used this shortcoming to their advantage to advance their imperial goals.
• Instead of attempting to establish a structured empire, the Marathas were constantly used to pillage areas outside their control. As a result, they never made an effort to improve their subjects’ social, economic, or cultural circumstances. As a result, their people’s allegiance was lost.
• After the 18th century, the Marathas lacked effective leaders and were forced to engage the outstanding English generals in several conflicts, which served as another major factor in the fall of the Maratha empire.

Summary

One of the most powerful regional kingdoms to emerge in Deccan following the fall of the Mughal Empire was the Maratha empire. By extending its rule from the Deccan to the northern regions of India when Shivaji assumed the Maratha throne, the kingdom began to resemble an empire. The Peshwas, who always posed a severe threat to the Mughal rule after Shivaji, also contributed significantly to the growth of this kingdom. The British could see the kingdom’s fragility after the Marathas were crushed in the Third Battle of Panipat. And finally, the Maratha chieftain’s submission to the East India Company in 1818 marked the end of this kingdom.

Frequently Asked Questions

1. What were Chauth and Sardeshmukhi?
Ans. Chauth was one-fourth of the total production that was given as a tax to the Marathas by non-Maratha territories as a token of safeguard for not invading these territories. Sardeshmukhi was the extra tax of 10% over Chauth that was to be paid as a homage to the Maratha ruler for ruling over non-Maratha lands.

2. What was the Guerilla warfare technique?
Ans. Guerilla warfare describes a style of conflict in which fighters with limited weapons participated rather than conventional military forces. These battles involved ambushes, raids, and surprise attacks.

3. Who was Ahmed Shah Abdali?
Ans. Afghanistan’s current government was established by Ahmed Shah Adali, who also served as king of the Durrani Empire. Eight times between 1748 and 1767, he invaded India. The Mughal empire suffered as a result of his repeated invasions.

Introduction 

All species, whether they have one cell or many, engage in diverse metabolic processes. The body produces harmful chemicals as a result of these processes. To prevent excessive accumulation of these waste products in the body, they must be excreted. The excretory system of the body performs the function of eliminating waste. Different species emit different wastes, and they are divided into 3 types- , Uricotelic, and Ammonotelic. The poisonous waste products produced by bodily metabolism must be eliminated from the body and this is done through the process of excretion. 

Excretion

Excretion is the process through which nitrogenous waste is expelled from the body. The excretory system in humans and the majority of chordates is responsible for the process of excretion. The human excretory system consists of two kidneys that filter the blood and remove the primary nitrogenous waste- Urea from the body. Nephrons, the kidney’s functional unit, filter blood and remove urea by the process of urine formation. Excretion is a very important step and it helps in maintaining the homeostasis of the body. Various organisms which stay in the abundance of water have their excretory products in the form of Ammonia and such are called ammonotelic organisms.

 Ammonotelism

• Ammonia is a waste product that some species, including amoeba, protozoa, echinoderms, Platyhelminthes, poriferans, cnidarians, and aquatic mammals, produce.
• These organisms are known as ammonotelic organisms and the process of excretion by such organisms is known as .
• To expel waste from their bodies, these organisms perform diffusion. The waste is excreted through their skin, gills, or kidneys.
• Ammonia has a small molecular size and it easily dissolves in water hence excretion is simple in aquatic animals.
• Elimination of ammonia from the body is very essential because when ammonia dissolves in water it generates ammonium hydroxide, which can result in necrosis of the tissues.
• Ammonotelism is the least energy-consuming and most water-intensive method of excretion. This is so because 1 gram of ammonia requires approx 500ml of water.

Physiological Aspect of Ammonotelic Excretion

• Fish and other aquatic species eat food that is high in protein and other nutrients.
• These organisms are unable to store amino acids for a long period, hence their intestines are designed for the deamination of amino acids.
• Uric acid is created during the process of deamination.
• Uric acid is oxidized which leads to the formation of  Allantoin and allantoic acid.
• Allantoin is hydrolyzed to form allantoate, and subsequent hydrolysis produces urea and glyoxylate.
• Urea is further broken down into ammonia and carbon dioxide in ammonotelic species.
• This ammonia then dissolves with the water and is expelled out of the body. 

Osmoregulation

Osmoregulation is the process of controlling the osmotic pressure of bodily fluids to maintain the water balance of the body. Since the cells of marine creatures are isotonic with saltwater, no regulatory mechanism is necessary. However, to keep the electrolyte balance in the body other organisms’ osmoregulation is a must. Osmoregulation helps maintain salts and water balance in the body. For instance, the antidiuretic hormone (ADH, also known as vasopressin) regulates the content of urine in humans. when the body’s water content is low More water is reabsorbed due to the presence of ADH. This leads to less urine production. More urine is produced when the body’s water content is high. Excretion and osmoregulation work in unison to make sure the steady state of the body is maintained.

Importance of Excretion

Excretion is a very important physiological process of the body. Its significance is given below.

• Excretion helps in the regulation of blood ionic composition.
• It helps in controlling blood pH.
• Regulation of blood volume and blood pressure is done through this process.
• It helps in maintaining blood osmolarity.
• The excretion of waste and foreign substances helps in cleaning the body of toxic and harmful wastes. 
• It assists in the maintenance of osmoregulation in the body.

Summary

Animals’ diets provide them with more amino acids. Ammonia, urea, and uric acid are excretory products that are created during the metabolism of proteins, amino acids, or nucleic acids. Organisms that are ammonotelic release ammonia as a waste product through their gills, skin, and kidneys. Removal of ammonia requires less energy. The regulation of water ion balance and homeostasis depends on the excretion of waste. By controlling the electrolyte balance, every organism keeps its internal environment in a steady state.

Frequently Asked Questions

1. Enlist excretory organs from different organisms.
Ans: Other excretory organs seen in various organisms are-

• Planaria – Flame cells
• Earthworm- Nephridia
• Cockroaches- malpighian tubules
• Prawns- green glands
• Molluscs- Renal glands

2. What are ureotelic and uricotellic organisms?
Ans: Ureotelic organisms – They release Urea as a waste product which is less toxic examples-Mammals and amphibians.

Uricotelic organism- They release Uric acid as a waste product which is the least toxic.  examples- Birds, reptiles, and insects.

3. Only aquatic animals are ammonotelic. Give reasons why?
Ans: Ammonia is highly toxic and hence cannot be stored in an organism’s body. Expulsion of ammonia from the body requires lots of water and hence aquatic animals such as fish only have the ability to form waste products in the form of ammonia.