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Introduction

Circuit boards, plastic light fixtures, switches, and sockets can all be made of the synthetic material known as Bakelite. The characteristics include non-absorbency and non-conductivity, as well as high-temperature resistance. Because it is utilized in electronic devices, it is referred to as “Bakelite.” A heated mixture of granular phenolic resin, sawdust, and asbestos is used to make Bakelite, which is then poured into a mould. The phenolic resin was the first artificial resin. Plastic materials come in a wide variety. 

Types of plastics

They can be divided into two classes: Thermoplastics and Thermosetting.

Thermoplastics: These are the plastic materials used to make the handles of toothbrushes and bags. Thermoplastics are heated to convert into their different forms.

Thermosetting: After heating, the hardness of this plastic increases. Bakelite is one type of thermosetting plastic.

Bakelite preparation

Bakelite is prepared by following such steps.

1. 25 ml glacial acetic acid is taken in a beaker. 12.5 ml 40% formaldehyde solution is mixed with it and heated.
2. After some time, 10-gram phenol is added to it and at the end 12-15 ml of HCl solution is mixed.
3. It is put in a water bath and heated gently until a solid mass appears.
4. Then it is passed through the funnel, fitted with filter paper, and Bakelite remains as a solid compound.

Structure of Bakelite:

In the Bakelite structure, there is a cross-linking between phenol and formaldehyde. Bakelite can be written chemically as\(\;{({C_6}{H_6}O – C{H_2}OH)_n}\).

Properties of Bakelite

1. Bakelite can be easily generated, and the mouldings of Bakelite are corrosion and thermal-resistant.
2. It would be resistive to current flow because of its low conductivity to electricity.
3. Due to its low electrical properties and high heat resistance, Bakelite has also been used primarily in the production of mechanical and electrical components for electrical devices.
4. Bakelite contains phenolic components in the structure. For this, it is widely used in bindings.
5. Bakelite is moulded at a very rapid rate. 
6. Bakelite enables the production of extremely smooth mould.
7. Bakelite can endure harmful solvents.
8. When heated, it melts and solidifies. Then It becomes hard and can be moulded into desired shapes.
9. The cost of moulding decreases when an inert filler is used.

Improving your Science concepts. Study Science Lesson for classes 6th, 7th, and 8th.

Uses of Bakelite

1. To offer adequate security, it is used in parts that do not use radios or other electronic parts, such as plugs, buttons, hoods, wire cables, brakes, and so on and due to its shaping capacity, it is frequently used in everyday culture.
2. Due to its strong tensile strength and thermosetting nature, Bakelite may maintain its shape even after extensive production.
3. It has the ability to mould itself in various shapes, making this substance too much useful in modern society.
4. It is extensively used in making the parts of washing machines, cooking utensils, watches, toys, and many more.

Importance of Bakelite

1. Due to its many important uses as the first synthetic polymer, Bakelite has been appropriately termed “a thousand-use material.” Bakelite is used in the production of many products, including handles of plastic, telephones, ATMs, and so on.
2. Due to its strong resistance to both heat and electricity, it is used to produce numerous electronic components, sensors, and vehicle parts.
3. Besides these, the features of Bakelite are improved in various ways for better uses.

     For these reasons, Bakelite is so important in our daily life.

Summary

Being one of the most widely utilized thermoplastic materials in the nation, it is used to produce many other polymers. It’s vital to remember that because of the distinct characteristics of such a polymer, changing the temperature has little impact on the physical and chemical characteristics of that kind of substance. Having phenolic components in its structure, it is widely used in bindings. But it is very dangerous for human health.

Frequently Asked Questions

1. What occurs when Bakelite is heated?

Ans: As a result of heating a Bakelite, a watery condensation compound (Known as Bakelite A) is produced. Bakelite A becomes dissolved in acetone, alcohol, or extra phenol. Additional heating makes the product somewhat soluble, though the heat can still soften it. The consequence of prolonged heating is the formation of “insoluble, hard gum.”

2. Is Bakelite able to resist fire?

Ans: The handles of many kitchen appliances (fry pans, pressure cookers) are made of sturdy and long-lasting plastic known as Bakelite. It is also a bad conductor of electricity and heat, just like Melamine.

3. Is Bakelite resistant to chemicals?

Bakelite is a tough and chemically inert plastic that was created by combining phenol and formaldehyde. These two substances were obtained from coal tar and wood alcohol (methanol) respectively. Bakelite is inert to chemicals.

Introduction 

The scientist, Antonio Lavoisier, introduced the law of conservation of mass in the year 1789. According to him, mass can’t be destroyed or generated. But mass can be transformed from one form to another. In our daily life, we also utilize this law. For example, in the burning process of wood, the total masses of the products (gases, ashes, soot) and the masses of the reactants (charcoal and oxygen)remain the same. 

Define “The Law of Conservation Of Mass”:

This law states: “matter cannot be created or destroyed in a chemical reaction”. That means the total masses of reactants or products should be the same after a reaction.

Application of the law of conservation of mass in different reactions:

1. During phase transition: During the transformation of any substance from its solid to liquid and then to vapour, the total mass of the substance remains constant. In the physical change of ice to water and then water to vapour, the mass of water in its three states remains the same.

Ice ⇌ water ⇌ vapour

2. During chemical reaction: Total masses of the reactants and the products remain the same after a successful chemical reaction. Like, in the combustion reaction of methane, carbon dioxide \(C{O_2}\) and water \({H_2}O\) are produced. The total masses of reactants (\(C{H_4}\)and \({O_2}\)) remain the same as the masses of products (\(C{O_2}\) and \({H_2}O\)).

\[C{H_4} + 2{O_2} \to C{O_2} + 2{H_2}O\]

3. During rearrangement reaction: Calcium carbonate produces calcium oxide and carbon dioxide on heating. The masses of reactants (calcium carbonate) and the products (calcium oxide and carbon dioxide)remain the same.

\[CaC{O_3} \to {\rm{ }}CaO{\rm{ }} + {\rm{ }}C{O_2}\]

Methods to examine the law of conservation of mass:

1. In the reaction of Barium chloride and magnesium sulfate: The law of conservation of mass can be proved by the following reaction. For this, some steps need to be followed.

• First, a particular amount of Barium chloride (\(BaC{l_2}.2{H_2}O\)) is weighed. Then some amount of distilled water is mixed with it. And this mixture is named A.
• Then some definite amount of magnesium sulfate (\(MgS{O_4}\)) is mixed with the same amount of water as A. This mixture is indicated as B.
• Then another empty beaker(C) is taken and weighed. The whole solution of A and B is poured into beaker C.
• A white precipitate of \(BaS{O_4}\) is formed in beaker C. Then the weight of beaker C is taken again.
• Now the weight of empty beaker C is subtracted from the beaker C, containing products.
• Comparing the masses of A, B, and C, we get that the total masses of the solutions A and B match with the product formed in beaker C.

In this way, the conservation of mass can be proved.

\[BaC{l_2} + {\rm{ }}MgS{O_4} \to {\rm{ }}BaS{O_4} + {\rm{ }}MgC{l_2}\]

2. In the reaction of silver nitrate and sodium chloride: This law can be proved by the following reaction of silver nitrate and sodium chloride. For this, the following steps need to be followed.

• Silver nitrate and sodium chloride solutions are made separately. Sodium chloride solution is taken in a conical flask and silver nitrate is taken in an ignition tube.
• Then the ignition tube is suspended into the flask and the flask is fitted with a cork.
• Now the mass of the conical flask is recorded, and then the conical flask is tilted for the reaction of silver nitrate and sodium chloride.
• Now, the product \(AgCl\) is precipitated as a solid. At this stage, the mass of the conical flask is recorded again.
• It is found that the masses of reactants and products are the same.

\[NaCl{\rm{ }} + {\rm{ }}AgN{O_3} \to {\rm{ }}AgCl{\rm{ }} + {\rm{ }}NaN{O_3}\]

Summary

The law of conservation of mass tells us that the mass of reactants and products is always the same after a reaction. That is, the total mass is always conserved in different types of chemical reactions as well as in physical changes. This law can be proved by some reactions in the laboratory. This law is very essential as the unknown mass of any reactant or product can be determined. From this law, any chemical reaction can be balanced easily.

Frequently Asked Questions

1. What are the drawbacks of the law of conservation of mass?

Ans: This law is valid for only chemical reactions and physical changes. But does not apply to nuclear reactions. During a nuclear reaction, heat is produced. That means some mass is converted to heat. So the mass is not conserved in the nuclear reaction.

2. Is there any difference between the conservation of mass and the conservation of energy?

Ans: Conservation of mass and energy were commonly considered to be separate concepts. However, special relativity demonstrates that mass and energy are linked by the formula \(E{\rm{ }} = {\rm{ }}m{c^2}\), and science currently holds the belief that the sum of mass and energy is conserved.

3. Which equation corresponds with the principle of mass conservation?

Ans: The law of mass conservation can be expressed by a balanced chemical equation. In a balanced chemical equation, the number of each element involved in a reaction is always the same on the reactants and products side.

Introduction

Chemical reactions operate on the type of reaction and change principle, which states that when a reactive substance interacts with other chemicals, different reactions will occur. Chemical reactions occur in stable or least reactive compounds as well, albeit under more extreme conditions. When reactants combine to produce a product, heat is released or absorbed, bubbles, gas, and fumes are formed, and the colours of the reactants change, resulting in a chemical change. During a  physical change, there is an interconversion of conditions. There are various types of chemical reactions, such as combination, decomposition, and displacement reactions, and certain changes occur during these reactions.

What is a Combustion Reaction

A combustion reaction is an exothermic chemical reaction that occurs between a fuel (or reductant) and an oxidant and results in the formation of oxidised products. This process occurs at high temperatures. This is a redox reaction because it involves the simultaneous reduction and oxidation of substances. A struck match, for example, generates friction, which raises the temperature (or energy) of the head (more than activation energy), at which the chemicals react and generate more energy in the form of heat, which tends to escape into the atmosphere. A moist matchstick head or the presence of blowing wind prevents the temperature from rising. As a result, the matchstick’s head does not burn. Another common example of combustion is the combustion of fuel in automobiles, which produces smoke.

Examples of Combustion Reaction

Methane combustion

Methane is a natural gas that burns the cleanest of all fossil fuels. The term “cleanest” refers to the absence of harmful toxins. It completely degrades into water and carbon dioxide.

Butane combustion

Lighters use the combustion process to break down butane. Butane is significantly less expensive than other fossil fuels. This is also a clean fuel, but it emits a lot of carbon dioxide into the atmosphere.

Butanol combustion

Butanol combustion occurs during the transportation process. Butanol has a high energy density and a low vapour pressure. As a result, it qualifies as a biofuel. Internal combustion engines, or IC engines, use this combustion process.

What is a Displacement Reaction

Displacement reactions occur when a portion of one reactant is replaced by another. A replacement reaction is another name for it. As one reactant ion is replaced by another. Single displacement reactions occur when one element removes another from its salt or complex. Single replacement reactions are another name for them. General representations can also be written –

\[A + B – C{\rm{ }} \to {\rm{ }}A – C + B\]

Examples of Displacement Reaction

• The reaction between Calcium Iodide and Chlorine.

\[Ca{I_2} + C{l_2} \to {\rm{ }}CaC{l_2} + {I_2}\]

• The reaction of Zinc with Hydrochloric Acid.

\[HCl + Zn{\rm{ }} \to {\rm{ }}ZnC{l_2} + {\rm{ }}{H_2}\]

Decomposition Reactions

A decomposition reaction is a chemical reaction that occurs when one reactant breaks down into two or more products.

The 2 main categories of these reactions are as follows

• The reaction of Thermal Decomposition:

It is a decomposition reaction that is triggered by heat energy.

E.g. \(CaC{O_3} \to {\rm{ }}C{O_2} + CaO\)

When heated, calcium carbonate breaks down into calcium oxide and carbon dioxide. Quick lime, a crucial component in several industries, is made using this process.

• The reaction of Electrolytic Decomposition:

Electrical energy is used to give the activation energy for a breakdown in an electrolytic decomposition process. An electrolytic breakdown reaction, such as water electrolysis, is exemplified by the chemical equation:

E.g. \({H_2}{O_2} \to {\rm{ }}{H_2} + {O_2}\)

Summary

It can be concluded that a displacement reaction occurs when one reactant is partially displaced by another. Displacement reactions are also known as replacement or metathesis reactions. The two types of displacement reactions are double and single displacement reactions. In a process known as double displacement, cations and anions in the reactants exchange partners to generate products: When a single reactant partially replaces another, a single displacement reaction occurs.

Frequently Asked Questions

1. What are combustible substances?

Ans. The substances that are easily flammable and undergo combustion are called combustible substances. For Example – LPG, CNG, wood, paper, clothes, etc.

2. What causes an exothermic displacement reaction?

Ans. When one element in a molecule is replaced by another, a single-displacement reaction takes place. A chemical reaction either releases or absorbs energy. If energy is released during the process, it is exothermic. The bond formation is an exothermic process.

3. Mention two uses of decomposition reaction.

Ans. Two uses of decomposition reaction are-

• This is used in the formation of cement or calcium oxide.
• This is also used for welding purposes.

Introduction

Aufbau is a German word that means “building up.” Like a construction build-up from the ground up. Atoms are also filled with electrons in this manner. An atom has orbitals that are arranged in increasing energy level order. According to the Aufbau principle, electrons are filled in the order of increasing energy of the atomic orbitals. That is from the bottom to the top. This principle aids in the electronic configuration of atoms as well as the placement of electrons in orbitals. In all atoms, the orbital is always the first orbital to be filled with electrons. After filling this orbital, electrons are filled in orbitals further away.

Explain Aufbau Principle

Niels Bohr, a Danish physicist developed the principle. According to this principle, the increasing order of energy levels of atoms causes the filling of electrons in an atom. They are entering a perfect order that corresponds to the energy level of orbitals.  We can predict the electron configurations of atoms or ions by using this rule.

The Madelung rule or rule is also related to this rule. According to this rule, the filling of electrons in an atom occurs as the value of n+l increases. That is, the electrons are filled to a lower-valued orbital. Where n represents the principal quantum number value, and l represents the angular momentum quantum number value. This is known as the Madelung rule or the diagonal rule.

Some features of the Aufbau Principle

1. Electrons are assigned to the subshell with the lowest energetically available energy.
2. An orbital can only hold two electrons.
3. If two or more energetically equivalent orbitals (e.g., p, d, etc.) are available, electrons should be spread out before being paired up (Hund’s rule).

Some Exceptions 

Some elements exhibit exceptional behaviour in terms of the Aufbau principle. They are chromium and copper, respectively. According to the Aufbau principle, the electronic configuration of chromium is \(\left[ {Ar} \right]3{d^4}4{s^2}\). However, chromium’s electronic configuration is \(\left[ {Ar} \right]3{d^5}4{s^1}\). And this is because chromium achieves stability by having a half-filled orbital. Elements require a filled state at all times. A fully-filled orbital is always more stable. Even though a half-filled orbital has partial stability.

Copper’s electronic configuration is \(\left[ {Ar} \right]{\rm{ }}3{d^{10}}4{s^1}\) rather than \(\left[ {Ar} \right]{\rm{ }}3{d^9}4{s^2}\). This is due to the presence of a fully-filled d-orbital configuration, which provides additional stability.

Summary

An electronic configuration is present for all elements to locate electrons in orbitals. As a result, the chemical properties of elements can be explained. When combined with other rules, this can result in a proper electronic configuration. According to Aufbau’s principle, the filling of electrons in an atomic orbital occurs in the order of increasing energy of atomic orbitals. The elements chromium and copper are exceptions to this rule. Because they achieve a half-filled and fully-filled atomic orbital, these elements can be more stable.

Frequently Asked Questions

1. Define Hund’s rule of maximum multiplicity

For an orbital of the same sub-shell, the filling of electrons takes place in a way that all the electrons are singly occupied before pairing occurs. The pairing of electrons takes place only when all the subshells are singly occupied.

2. What do you understand by Pauli’s exclusion principle?

All the quantum number values are distinct for each electron present in an atom. This principle states that no two electrons in an atom can have an equal set of all the quantum number values. And thereby we can easily locate all the electrons in an atom.

3. What is the principal quantum number?

The number that deals with the energy and size of orbitals are a principal quantum number. It will explain how far an electron is from the nucleus. For example, the electronic configuration of Helium is \(1{s^2}\) so the principal quantum number is 1.

Introduction

We come across several items of various shapes and sizes in our daily lives. Many items have three sides, whereas others have four, five, and so on. Some forms have equal sides on all sides, whereas others do not. Consider our laptop screen, deck of cards, tabletop, chessboard, carrom board, and kite as examples. What feature does each of these shares? Each of them has four sides.

A quadrilateral is a flat shape with four straight sides. The terms Quadra and Latus combine to make the word quadrilateral. Quadrilaterals are simply shaped with four sides since Quadra means “four” and latus means “sides” in Latin.

One definition of a quadrilateral is a closed four-sided shape. There are many different types of quadrilaterals, including square, rectangle, rhombus, trapezium, kite, etc., supported by the characteristics of sides and angles.

Quadrilaterals

A quadrilateral is a polygon with at least and at most four sides, four angles, and four vertices.

Just like every other polygon, except triangles, the quadrilaterals are also divided into two subcategories,

1. Concave Quadrilaterals: These quadrilaterals have one diagonal passing through outside of the body of the quadrilateral. The following image shows one example of such quadrilateral 
2. Convex Quadrilaterals: These are the normal quadrilaterals, that have all the angles less than \(180^\circ \) , and both the diagonals are always contained within the quadrilaterals.

These are divided into \(2\) more categories

1. Regular: In these quadrilaterals all four sides and all four angles are equal to one another. The only regular quadrilateral is Square.
2. Irregular: In these quadrilaterals, all four sides or all four angles are not equal to one another. There are many irregular quadrilaterals, such as, Rhombus, Rectangle, Trapezium etc.

Properties in Quadrilaterals

Above, we have a quadrilateral \(ABCD\) 

• This quadrilateral has \(4\) sides, and they are \(AB,BC,CD\) and  \(DA\) .
• This quadrilateral has \(4\) vertices, and they are \(A,B,C\) and \(D\) .
• This quadrilateral has \(4\) angles one at each vertex.

Angle Sum Property of a Quadrilaterals

The Angle Sum Property of a Quadrilateral states that the sum of a quadrilateral’s four internal angles is \(360^\circ \) .

I.e., in above example of Quadrilateral ABCD, we have,

\[A + B + C + D = 360^\circ \]

Types of Quadrilaterals

In this section, we will discuss the different types of quadrilaterals and some of their properties.

Square

This is the regular quadrilateral, i.e., all four sides and all four angles are equal to one another. The diagonals are also equal, and bisect each other at right angles. By the property of regular quadrilateral and angle sum property, the angles of the square are right angles.

Rectangles

Rectangles have opposite sides equal and parallel, and all four angles in rectangles are right angles. The diagonals are equal, and they bisect each other but not at right angles.

Also Read: Exterior Angles of a Polygon

Rhombus

Rhombus’ have opposite angles equal, and all four sides in rhombus’s are equal. The diagonals bisect each other at right angles.

Parallelograms

Parallelograms have opposite sides equal and parallel, the opposite angles are also equal in a parallelogram. Diagonals bisect each other.

Trapezium

Trapeziums have only one property, i.e., they have one pair of opposite parallel sides. Other than that they can have any side lengths, any angles, and any diagonals.

Summary

This article taught us about quadrilaterals, including their kinds and qualities. A \(2D{\rm{ – }}shape\) with four sides, four vertices, and four angles is referred to as a quadrilateral. Quadrilaterals come in a variety of shapes, including rectangles, rhombus, squares, trapezoids, parallelograms, and kites. These all feature unique angles and side characteristics.

Frequently Asked Questions

1. Are all parallelograms rectangles? What about the other way around?

Ans. No, all parallelograms are not rectangles. Since to be a rectangle a parallelogram should have diagonals equal, they should also have all the angles to be right angles. Which is not the case for parallelograms. Whereas if we see it other way around, we have the pair of opposite sides parallel and equal to each other and the diagonals also bisect each other, thus all rectangles are parallelograms.

2. What are the properties of a kite?

Ans. Kite is a convex quadrilateral with pair of adjacent sides equal to each other and the diagonals are perpendicular to each other. Also, the diagonal between the equal sides bisects the other.

3. A square has the properties of all three, parallelogram, rectangle and rhombus. Justify this statement.

Ans. A square has following properties.

• Opposite sides parallel and equal. (Parallelogram)
• Opposite angles equal. (Parallelogram)
• Diagonals bisect each other. (Parallelogram)
• Diagonals are equal. (Rectangle)
• All the angles are equal to right angles. (Rectangles)
• All four sides are equal. (Rhombus)
• Diagonals are perpendicular bisectors of each other. (Rhombus)

Thus it is clear that the square has the properties of all, parallelogram, rectangles and rhombus.

Introduction

Transport is a crucial component of plant physiology and involves moving organic nutrients and water throughout the plant body. Food is produced by photosynthesis in the leaves which is transported to other parts of the plant and water is absorbed from the soil through the roots and then to various aerial regions of the plant. In higher plants, the transport of food and water takes place through specialized structures known as the xylem and phloem. An elaborate root system helps these plants to absorb water from the soil.  However, primitive plants perform the function of absorption of water through simple structures such as pores, or the external body surface.

For more help, you can Refer to our video in Class 7 Science in Lesson no 11. Check out the video Lesson for a better understanding.

Transportation in plants-

The main 3 means of transport in plants are via diffusion, Facilitated diffusion, and Active transport. Vascular bundles assist in the movement of water and carbohydrates throughout the entire plant body.

Simple Diffusion- Diffusion is the process of movement of a molecule from a location of higher concentration to a lower concentration i.e. along the concentration gradient. It is a spontaneous process and doesn’t require any energy. Here no special membrane proteins are required and this method only allows the transportation of hydrophobic molecules as the cell membrane is made up of a lipid bilayer.

• Facilitated diffusion- Facilitated diffusion is a type of diffusion facilitated by some proteins which assist in the movement of various metabolites through the cell membranes. These are majorly used for the transportation of water, ions, and other hydrophilic molecules which cannot pass through the lipid bilayer. The channel proteins and the carrier proteins are the two different types of membrane transport proteins.
• Channel proteins- Pores in the plasma membrane are created by channel proteins. These proteins are highly selective and hence allow the transportation of specific molecules only. Eg-Aquaporins only permit water movement and Aquaglyceroporins facilitate only the movement of glycerol and water.
•  
• Carrier proteins- These are special types of proteins that undergo conformational changes after binding to a particular solute. Carrier proteins help in the transportation of ions eg- chloride-bicarbonate exchanger, also known as the anion exchange protein, which facilitates the simultaneous transit of HCO3- and Cl–. It also helps in the transport of glucose via the glucose transporter(GLUT).
• Active transport- Active transport facilitates uphill solute movement throughout the cell by functioning against a concentration gradient. Here the molecules move from an area of lower concentration to a higher concentration. Hence, some kind of energy is required. There are two ways to supply energy:

• The energy produced by ATP hydrolysis is known as primary or direct active transport. For instance, the energy is given through the Na+-K+ ATPase (electrogenic pumps). 

• The energy supplied through the electrochemical gradient is enabled by the Symport pumps (such as the Na+-Glucose symporter, lactose permeases, etc.) and Antiport pumps (such as the Na+-Ca2+ antiporter) These are often referred to as secondary or indirect active transport.

Transport of water from roots

Long-distance transportation of water and nutrients in plants takes place through the xylem and phloem. The soil-plant-atmosphere continuum (SPAC) is a pathway that discusses the movement of water from the soil, its transportation to plant parts, and 

the expulsion of water from the plant. Absorption of water in plants occurs through-Passive absorption- when water is absorbed from a higher water potential (in soil) to a lower water potential (in root cells). Active absorption-which occurs due to transpiration.

Ascent of sap

The term “ascent of sap” refers to the movement of water and minerals from the soil to aerial portions like leaves and stems. The cohesion-tension theory, also known as transpirational pull, explains this (Dixon and Jolly, 1894). According to this idea, water from locations with higher water potential (such as the roots) is drawn up, to areas with lower water potential (the leaves)  due to the tension (negative hydrostatic pressure) which is generated by the leaves. There is low water potential in the leaves because they lose water due to the process of transpiration. The water column is kept from collapsing by the cohesive forces of attraction between the water molecules. As a result, water absorption happens to make up for the transpirational loss.

Summary

Intricate transportation networks are needed by plants to enable the interchange of materials and nutrients. The passive process of moving molecules from higher to lower concentrations is known as diffusion. It could be simple (independent) or facilitated transport. Energy is spent during active transport, which is carried out by membrane proteins called transporters and channel proteins. The transpirational pull/cohesion-adhesion principle is used by the roots to absorb water. 

Frequently Asked Questions

1. What do you understand about water potential?
Ans: The potential energy of water per unit volume is referred to as water potential. It describes the amount of water in the atmosphere, plants, and soil.

It is shown as the sum of Osmotic potential, matrix potential, hydrostatic potential, and gravitational potential. 𝜳w = 𝜳𝛑 (osmotic potential)   + 𝜳m (matrix potential)  +𝜳p (hydrostatic potential)  +  𝜳g (gravitational potential).

2. What is the symplastic pathway of water absorption?
Ans: The continuous network of cell cytoplasms is known as the symplastic route.

Through the plasmodesmata connections present between two cells, this pathway allows absorbed water to flow from cell to cell.

3. Which method of water absorption is quick?
Ans: The apoplastic pathway will move more quickly since there won’t be as many obstacles in its path as there are in the symplastic pathway, which is obstructed by Casparian strips and must travel through the protoplasm, which slows down movement.

Introduction

Evolution is an intricate and slow process. Various organisms constantly adapt by changing their morphological and anatomical characteristics in response to the change in the environmental conditions of their habitat. They make minor changes in their genetic composition to adapt to their surroundings and thrive in their niche. These, minor alterations in their genes are responsible for the formation of new species. Adaptive radiation is one such process by which organisms of a single species rapidly transform into distinct forms to propagate successfully and thrive in their niche.

Factors causing adaptive radiation

Various factors are causing adaptive radiation some of them are-

• Geographical isolation– Geographic isolation of organisms from the mainland due to the formation of valleys, mountains, earthquakes, etc. becomes one of the main reasons for adaptive radiation to take place. This sudden separation causes organisms to rapidly adapt to new changes and hence evolve.
• Exposure to new habitat– When organisms are exposed to new habitats, they are exposed to lots of new resources which are available abundantly. This abundance of resources forces them to diversify and adapt in a way that they can exploit those resources to the maximum and thus cause the evolution of new features.
• Changes in environmental conditions- Change in environmental conditions can occur due to floods, volcanic eruptions, deforestation, weather changes, etc. These changes are sudden and hence force the organisms living in particular habitats to change rapidly and hence lead to adaptive radiations.

All of the above factors cause a change in the genetic composition of the organisms and hence lead to the formation of new and permanent changes in their genotype which then in turn leads to the formation of newer species.

Distinctive features of Adaptive radiation

Distinctive features of adaptive radiation which separate it from other evolutionary changes are as follows-

• Common ancestry- Organisms that undergo adaptive radiation belong to the same ancestor. 
• Phenotype-environment correlation- The changes in the phenotype of the species are with the change in the environmental conditions. 
• Trait utility-The new trait thus formed due to adaptive radiation helps the organisms to survive in the new environment. For eg-Darwin’s finches.
• Rapid speciation-This adaptation is a very rapid process as the organisms need to quickly adapt to the changing environment for their survival.

Adaptive radiation in mammals

Adaptive radiation can be studied by various examples once such as limb structure in mammals which is used for locomotion.

• Modern placental mammals are incredibly diverse in terms of size, behavior, and many other features. They may be found practically anywhere in the world.
• These mammals are descended from a little, short-legged, terrestrial predecessor that consumed insects.
• The pentadactyl (five-fingered) small legs belonged to the insectivorous ancestor. Despite being terrestrial, the appendages cannot move the creature.
• The extinction of dinosaurs suddenly caused the remaining mammals to undergo fast diversification. This gave rise to a variety of modern mammals through the process of adaptive radiation.

Mammals followed five separate evolutionary lines and evolved features to fit their respective surroundings, these adaptations are-

• Arboreal placental animals- These are climbers and are generated by growing appendages with grabbing capabilities. Example: Monkeys and tree-dwelling squirrels.
• Aerial placental mammals- These mammals can fly. They evolved limbs into flying wings. Examples- are gliding squirrels and bats.
• Aquatic placental mammals- These can swim in the water. They have appendages that are designed specifically for swimming and surviving in water. Examples- Whales, dolphins, seals, polar bears, sea lions, and walruses.
• Fussorial placental mammals- These are burrowing mammals and bear strong pentadactyl limbs allowing them to dig down far into the ground. Example- moles and badgers.

Cursorial placental mammals- These mammals evolved limbs to allow for swift ground movements such as running, climbing, walking, etc. Examples-wolves, are horses, pigs, antelopes, and lions.

Even though each of the aforementioned groups of placental animals has limbs that are specific for particular habitat, they all shared a common ancestor that had pentadactyl limbs. These evolutionary lines that radiated out in different directions served the purpose of locomotion in their respective habitat.

Summary

Understanding adaptive radiation aids in the comprehension of how organisms interact within a given habitat. Although the food web provides clear knowledge of species interactions, examining adaptive radiation evolution might help us understand how species are dependent on one another. Adaptive radiation enables us to gain new insights into the environmental changes which influence evolution.

Frequently Asked Questions

1. Does adaptive radiation favor biodiversity?
Ans: When a common ancestor diversifies into various forms to fit into the new environment it is known as adaptive radiation. The newly developed adaptive species then gradually diverge from their ancestor until they no longer resemble them. Since adaptive radiation occurs quickly and in multiple directions at once, it leads to biodiversity.

2. How does adaptive radiation operate?
Ans: As a result of being exposed to new ecological conditions, organisms constantly diversify. They do this to take full advantage of the environmental conditions. Therefore, the process of adaptive radiation has been continuously driven by the formation of new ecological niches which increase the availability of newer resources for survival.

3. Is it accurate to say that only species with the ability to move can benefit from adaptive radiation?
Ans: Moving to a new environment is not the only way for an organism to adapt or experience a different environment. Adaptive radiation can also affect sessile plants. For instance, a single common ancestor gave rise to 28 species of Hawaiin silverswords. They belong to three distinct genera and fill various niches.

Introduction

The electronic configuration describes the distribution of electrons within an atomic subshell. An electron configuration is a summary of the prediction of the position of the electrons surrounding a nucleus. In every neutral atom, the electron number is the same as the proton number. Now we’ll arrange those electrons so that they form a ring around the nucleus, displaying their energy and the orbital type in which they are located. Electrons occupy orbitals in a specific order based on their energy.

What do you understand by Electron Configuration?

• The electronic configuration describes the distribution of electrons within an atomic subshell.
• Atomic electronic configurations follow a standard format in which each atomic subshell containing an electron is listed in ascending order.
• For high atomic numbers, the standard representation of electronic configuration can be quite lengthy. In some cases, an abbreviated/condensed symbol may be used instead of the standard representation.
• The electron configuration of Na, for example, is \(1{s^2}2{s^2}2{p^6}3{s^1}\).

How Subshells are important for Electron Configuration?

• The azimuthal quantum no., represented by the letter “l,” determines the distribution of electrons into subshells.
• The magnitude of the principal quantum no., n, dictates the magnitude of this quantum number. As a result, when n equals 4, four distinct subshells can exist.
• For n = 4, the s, p, d, and f subshells correspond to l=0, 1, 2, 3 quantities.
• Equation 2(2l+1) gives the maximum number of electrons that a subshell can hold.
• The s, p, d, and f subshells can hold a maximum of 2, 6, 10, and 14 electrons, respectively.

Atomic Electronic Configuration Representation

This section provides examples of a few elements’ electronic configurations.

• The electron configuration of hydrogen has an atomic number of one. As a result, an H atom has one electron, which will be assigned to the subshell of the first shell/s orbit. \(1{s^1}\) is the electronic configuration of H.
• The electron configuration of chlorine

Cl has the atomic number 17. As a result, its 17 electrons are distributed as follows:

The K has two electrons.

The L has 8 electrons and the M has 7 electrons.

The electron configuration of Cl is depicted below. It is written as \(1{s^2}2{s^2}2{p^6}3{s^2}3{p^5}\).

Filling Atomic Orbitals

The following concepts govern how electrons are occupied in atomic orbitals.

Aufbau Principle

“The energy of an atomic orbital is calculated by adding the principal and azimuthal quantum numbers, and according to the Aufbau principle, electrons begin in relatively low energy orbitals and progress to higher energy orbitals.”

Pauli Exclusion Principle

“Only electron pairs with opposite spins can be carried in an atomic orbital, and no two electrons in the same atom have the same values for all four quantum numbers. If two electrons have the same principle, azimuthal, and magnetic numbers, they should have opposing spins.”

Hund’s Law

“Before a second electron is placed in an orbital, each orbital in a specific subshell is said to be entirely filled by electrons.”

Summary

It can be concluded that Electron configuration is the depiction of electron distribution inside an element’s atomic shells. Because the electrons are mathematically positioned in these subshells, the configuration aids in determining their position. The periodic table categorises elements based on their electron configurations. These make up the s, p, d, and f-block elements. The maximum number of electrons that can fit in a shell is determined by the principal quantum number (n). The azimuthal quantum number, represented by the letter “l,” governs the distribution of electrons into subshells.

Frequently Asked Questions

1. Why are specific electron configurations required for elements?
Ans. Electron configurations can shed light on an atom’s chemical behaviour by identifying its valence electrons. It also aids in the organisation of elements into different blocks such as s, p, d, and f blocks.

2. Describe the significance of electron configuration.
Ans. The significance is as follows:

They aid in determining the reactivity state of an atom.

It aids in the identification of both chemical and physical properties.

It foretells an atom’s magnetic properties.

3. For n=3, which subshells are present?
Ans. Each orbital can hold a maximum of two electrons, and there are four subshells present- s, p, d, and f for n=3. The maximum number of orbitals corresponding to the s, p, d, and f subshells is 1,3,5, and 7.

Introduction

Numerous independent and semi-independent regional powers emerged as a result of the Mughal Empire’s decline. The Jats were agricultural settlers who lived in the areas surrounding Delhi, Agra, and Mathura. They were outraged by Aurangzeb’s repressive policies and began to rebel against the empire. Under the leadership of Gokul, one of the Tilpat zamindars, these revolts began in 1669. After some initial challenges, they were successful in creating the new Jat state of Bharatpur, which was led by Churaman and Badan Singh. Under Surajmal, this Jat state of Bharatpur attained its pinnacle. He not only established a productive government but also greatly increased the size of this empire. This state covered the areas from the Ganges in the east to Chambal in the south. Subas Agra, Mathura, Meerut, and Aligarh were also added to the state.

Expansion of Jat power (1680-1707)

There were many leaders of the farmer community, who raised their voices against the oppressive systems of the Mughals. This peasant group has several leaders who spoke out against the Mughals’ repressive regime. Brij Raj of Sinsini was one such ruler during the seventeenth century who joined up his forces with the other Jat rebels to form an alliance against Mustafa Khan, the faujdar of Agra. He was instrumental in bringing together the people who wished to refuse to pay the taxes demanded by the Mughal government. Even though the local faujdar had earlier promised to assist in this case, he ultimately decided to commit suicide alongside other villagers rather than pay the money. The faujdar Multafta Khan was ultimately conquered by Brij Raj after calling for a major fight with the faujdar’s army.

Raja Ram, the son of Bhajja Singh, was another great representative of the Jat caste (Brother of Brij Raj). By engaging in looting and plundering within the Mughal territory, he issued a severe challenge to the Mughals. He created a true standing army out of the Jat communities after learning from the failure of Gokula’s uprising. He understood how crucial it is to have a well-equipped army to combat the well-equipped armies of the Mughals. And to accomplish this, he began forming alliances with the chieftains of other Jat clans. For security, he even began constructing forts in the deepest parts of the jungle and started practicing guerrilla warfare techniques.

The northern region of the Mughal empire began to deteriorate when Aurangzeb was occupied fighting Marathas in Deccan. Jats recognized a benefit in this. To weaken the emperor’s hold over the undefended Mughal lands close to Agra, they began launching incursions there. They even attempted to raid Akbar’s tomb in Sikandra. They ultimately ran upon Abul Fazal, the local faujdar, who had defended Akbar’s tomb and the Mughals from this Jat invasion.

In 1688, Raja Ram returned to Sikandra, and this time he was successful in looting from Akbar’s grave. Aurangzeb was so outraged by the Jats‘ behavior that he despatched his grandson Bidar Khan to put an end to the Jat rebels. The Rajputs of Chauhan and Shekewat were engaged in conflict during the time. Raja Ram sided with Shekhawat, whereas Bidhar Khan sided with Chauhan. Raja Ram was killed in this combat in 1688 by a Mughal musketeer.

Prosperous agriculturalists

In the northwest of the Indian subcontinent, the Jats were the largest community (India and Pakistan). This community was made up of Indian Hindus and Sikhs.

They started as sheep and cattle herders, but eventually switched to farming as their primary activity. Due to the development of the Indus valley civilization, when people began settling down along the Indus River, the Jats likely became farmers due to this reason. Additionally, the Indus River supplied a rich area and sufficient water for farming. They began to rule the region between the two significant Mughal states of Delhi and Agra in the 1680s. Under their rule, the two significant states of Panipat and Bhallabhgarh developed into significant commercial hubs. Over time, this landowners’ community rose to prominence in different regions like Punjab, UP, Delhi, and Haryana.

Surajmal and the kingdom Bharatpur emerged as a strong state

The Jat community’s ongoing uprising against the oppressive Mughal rules eventually resulted in the establishment of Bharatpur as an independent Jat state under the leadership of SurajMal. Under the direction of Sadat Khan, the Mughals attempted to siege Bharatpur.

And one of the outposts was successfully captured by the Mughals. However, as soon as Raja Surajmal learned of this, he attacked them and trapped the Mughal camp. Later, Sadat Khan reached a settlement and left Bharatpur. Raja Suramal offered Chaudhari Charan Das protection in 1792 from Murtaza Khan (the governor of Faridabad) and the royal Farman was issued by the Mughals. Even one of the Rohilla nawab told Safdar Jang, (the Mughal grand wazir), that this Jat could not be vanquished. The Mughals took this counsel to heart and took no more action against the Jat. Faridabad was granted to Surajmal as Chaudary Charan das’ jagir. This strengthened the bonds between the Mughals and Jat.

When Ghazi-ud-din ousted Safdar Jang as grand wazir, he decided to seek revenge on Surajmal, this flared tension between Jats and Mughals once more.

He besieged the fort in 1754 with the assistance of Maratha. For three months, this siege went on. A Jat rani Kishori Bai requested their assistance and hence the Marathas were forced to assist the Jats in their fight against the Mughals.

As a result of Ahmed Shah Abdali besieging the fort of Dig and demanding a tribute that Surajmal was unable to pay, Surajmal then had to battle with Afghans. After a while, Abdali lifted the siege and left the region, but he returned in 1760 to besiege another Koli fort (modern-day Aligarh). After that, Suraj Mal once more decided to conquer Agra Fort to reclaim his power in the Doab region, and he managed to accomplish so. Surajmal eventually lost his life during a battle with Rohillas under Najib-ud-daulah. However, upon Surajmal’s passing in 1763, the Jat state started to crumble.

Summary

Several kingdoms attempted to declare their independence from the Mughal rule as the Mughals fell apart. One of them was the Jats, who were displeased and outraged by Aurangzeb’s anti-Hindu actions. The Jat communities began to rebel against these rules in the second half of the 17th century. All of these uprisings opened the stage for Badan Singh to build the Jat state of Bharatpur. Raja Surajmal deserves all the credit for uniting these Jat rebels and turning Bharatpur into a Jat stronghold. The Jat kingdom, however, started to fall once the powerful commander Suraj Mal passed away since none of his successors could manage the country as effectively as he had.

Frequently Asked Questions

1. What and when did the Gokula Rebellion happen?Ans: Gokula Singh, a Jat zamindar of Tilpat, served as the head of the Gokula uprising in 1669. By withholding the extra land tax, he questioned the Mughal government’s authority.

2. Which of Aurangzeb’s measures offended the Jats‘ religious beliefs?
Ans: The Jat group was most outraged by Aurangzeb’s anti-Hindu religious agenda. He implemented several actions, including jizyah imposition, temple destruction, conversion to Islam, and religious persecution. The Jats became disgruntled as a result of Aurangzeb’s these actions.

3. Who was Sadat khan?
Ans: As the governor of Awadh, Sadat Khan, also known as Nizam-ul-Mulk, served. Later, as he fought alongside the Mughal emperor in the Deccan campaign against the Marathas, Aurangzeb bestowed upon him the title of “Khan Bahadur.” He was very well-known as the creator of the Awadh principality,

Introduction

All plants and animals depend on other plants or animals to survive. A example might be a lion consuming a deer or a deer feeding on shrub leaves. In order to depict how energy and nutrients travel through an ecosystem, food chains and food webs were created. In addition to helping us understand the living things that make up an ecosystem, these food chains and webs manage the energy flow within the ecosystem.

Food Chain

A food chain,is simply an orderly series of actions taking place in an environment where one living organism consumes another one. It is a network of living things that makes up an ecosystem and on which each member depends for sustenance and energy.Food chain includes producers, consumers, and decomposers. The producers are the green plants, then the consumers are other animals, the decomposers are the microorganisms.

There are four basic trophic levels in a food chain. They are as follows:

• Sun-The sun is recognised as the fundamental source of nourishment for creating food and supporting growth and development.
• Producers-Green plants are among the producers that make up the first link in the food chain.

Consumers-Any species that eats other organisms is a consumer. This is thought to be the largest part of the food chain in the environment.

• Decomposers-Decomposers are organsisms that decompose the organic content of various plants and animals. They  receive their energy from this organic waste  from the dead objects.

Types of the food chain

There are basically two types of food chain- The terrestrial food chain and the Aquatic food chain. The terrestrial food chain is seen on the land whereas the Aquatic food chain is seen in water bodies. Examples of food chains are given below.

Terrestrial food chain

• Nectar (flowers) → butterflies → small birds → foxes
• Dandelions → snail → frog → bird → fox
• Rice → rat → owl
• Leaves → giraffes → lions → jackals
• Leaves → caterpillars → birds → snakes
• Grass→ antelope → tiger → vulture

Aquatic food chains

• Phytoplankton→Zooplankton→Small fishes→Medium fishes→Mahi mahi→Large sharks

Food web

A system of linked food chains is referred to as a “food web”. A food web is made up of different species from the population. There is a common element throughout all of these, namely the requirement for energy to complete the tasks. Most importantly, the sun is the planet’s main source of energy. Green plants use this energy to create food. Once they have captured the energy, it is next transformed by a variety of local organisms in what is known as a food web.The complex and interrelated food networks that make up the food web can be isolated or separated without impairing the ecosystem’s ability to function. As a result, if one organism is removed from it, the flow of nutrients and energy won’t be impacted. Additionally, they exist in several biomes.The variations in each habitat cause a small variation in each food web.

Types of the food web

• Connected Food Web: Scientists use arrows to illustrate how one species is consumed by another in a connected food chain. Each arrow has the same weight. How effectively one species can eat another is not shown.
• Interaction Food Web : Scientists use arrows to depict one species being consumed by another, just as they do in connected food webs. The weight of the arrows here represents how much one species consumes the other. If one species often consumes another, the arrows shown in such arrangements may be wider, bolder, or darker to reflect the intensity of consumption. The arrow may be very small or not there if the connection between the species is extremely less.
• Energy flow food webs: Food webs that quantify and depict the energy flow between species are used to illustrate the movement of energy and the connections between the organisms in an ecosystem.
• Fossil Food Webs: Just as the food chains that make up an ecosystem can evolve over time, so too might the food webs themselves. Using data from the fossil record, scientists try to reconstruct species relationships in an ancient food web.

Difference between Food web and Food chain

Food chain	Food web
Energy moves from a lower trophic level to a higher one along a single, direct conduit.	The various interconnected food chains are where the ecosystem’s energy flow occurs.
There is only one straight chain in it.	It is made up of numerous interrelated food chains.
Movement of nutrients and energy via a single linear pathway.	Numerous linked channels where nutrients and energy travel.
It rises as a result of the expansion of isolated, small food chains.	Due to the existence of complicated food chains, it grows.
Includes 4-6 trophic levels of various species.	Includes several trophic levels of various species populations.
A single species of lower trophic level organism is fed upon by members of the higher trophic level.	Different kinds of lower trophic level species are consumed by members of higher trophic levels.
If even one group of an organism disrupts, it has an impact on the entire chain.	The removal of one group of species has no effect on the food chain.

Summary

A food chain is a straightforward network that shows the linear movement of nutrients and energy from one trophic level to another. A group of interconnected food chains at different trophic levels is known as a food web.A food web also accurately depicts all the many food chains that are present in an environment.

Frequently Asked Questions

1. Who gave the concept of food web?
Ans: Charles Elton is regarded with originally introducing the concept of a food web, commonly referred to as a food cycle, in the year 1927. In his book named Animal Ecology he gave the concept of food web.

2.What are the components of an arctic food chain?
Ans: An arctic food chain is made up of various organisms such as –

Alage→Planktons→Krill→Artic cod→Leapord Seal→Polar bear.

Here- Algae are the producers, Planktons are primary consumers, Krill, Artic cod and Leapord are secondary consumers and Polar bear is the apex consumer.

3.How energy flows in an terrestrial ecosystem?
Ans: In an terrestrial ecosystem the energy flows from producers to the apex consumers. But the energy goes on decreasing as it moves up  from the producers to the apex consumer. Thus the energy pyramid, here is upright and straight.In this transfer of energy from one tropic levels to the next only 10% of the energy is passed, remaining energy is lost.