Tag: Water

Introduction

Biodegradable and non-biodegradable substances refer to the materials that make up the products and waste we use and discard in our daily lives. Biodegradable substances are made from organic materials and have a positive impact on the environment when properly managed and disposed of. Non-biodegradable substances, on the other hand, are made from synthetic materials and do not break down in the natural environment. It is important to minimize our use of non-biodegradable substances and properly manage both biodegradable and non-biodegradable waste in order to protect the environment and promote sustainability.

Biodegradable Waste and Biodegradable Material

Biodegradable waste materials are materials made from organic matter, such as starch-based plastics or plant-based fibers, which can be broken down by natural processes into the water, carbon dioxide, and biomass. Unlike traditional plastics, which can persist in the environment for hundreds of years.

Examples of Biodegradable substances

Some common examples of biodegradable substances include:

• Food waste, such as fruit and vegetable scraps, bread, and meat
• Yard waste, such as leaves, grass clippings, and tree branches
• Paper products, such as newspaper, paper towels, and cardboard
• Textiles made from natural fibers, such as cotton or wool
• Biodegradable plastics made from renewable materials, such as corn starch or sugarcane
• Manure and sewage sludge
• Wood chips and sawdust.

Non-Biodegradable Waste and Non-Biodegradable Material

Non-biodegradable material refer to a material that does not break down into natural substances over time and persist in the environment for long periods. These materials are typically synthetic, made from petrochemicals, and do not decompose in the natural environment.

Non-biodegradable waste refers to discarded items made from non-biodegradable materials that cannot be decomposed by natural processes. Examples of non-biodegradable waste include plastic bags, polystyrene packaging, and aluminum cans. Unlike biodegradable waste, non-biodegradable waste can persist in the environment for hundreds of years and can cause environmental problems if not properly disposed of.

Examples of Non-Biodegradable substances

Some common examples of non-biodegradable substances include:

• Traditional petroleum-based plastics, such as polyethylene (PE) and polypropylene (PP)
• Aluminum cans and foil
• Glass bottles and jars
• Metal products, such as steel cans and car parts
• Electronic waste, such as computers, phones, and televisions
• Synthetic fibers, such as nylon and polyester
• Certain types of synthetic rubber and paints
• Fire retardants and flame-retardant materials.

Effect of Biodegradable and Non-Biodegradable Substances on the environment 

The effects of biodegradable and non-biodegradable substances on the environment can vary greatly.

• Biodegradable substances, such as food waste and yard waste, can have positive impacts on the environment when properly managed. For example, food waste can be composted and added to soil as a natural fertilizer, improving soil health and reducing the need for chemical fertilizers. Yard waste can also be composted, or used as mulch to retain moisture in the soil.
• On the other hand, non-biodegradable substances can have harmful impacts on the environment. When not properly disposed of, non-biodegradable waste, such as plastic bags and polystyrene packaging, can litter the environment, harm wildlife, and take hundreds of years to break down. Landfills overflowing with non-biodegradable waste can also release toxic substances into the air and water, causing further harm to the environment and human health.
• In addition, the production of non-biodegradable materials, such as petroleum-based plastics, can contribute to greenhouse gas emissions and other environmental problems associated with the extraction and processing of fossil fuels. 
• When these wastes build in the soil, they affect the pH and fertility of the soil. Non-biodegradable trash should be reused, reduced, or repurposed rather than dumped into oceans, as this constitutes a significant environmental risk.

Overall, it is important to properly manage both biodegradable and non-biodegradable substances in order to minimize their negative impacts on the environment.

Differences between biodegradable and non-biodegradable substances:

Conclusion

Biodegradable compounds are those that can be broken down or decomposed by the action of microbes or any form of life, whereas non-biodegradable substances are those that cannot be broken down into little pieces by the action of any kind of life. Organic wastes that degrade quickly are considered biodegradable wastes. Plastics and glassware are examples of non-biodegradable garbage that require thousands of years to disintegrate. All sorts of garbage affect our environment and all types of life on the planet. As a result, waste treatment is critical, which includes recycling, reusing, and decreasing.

 

Frequently Asked Questions 

1. What is the three R’s stand for?

The “Three R’s” stand for Reduce, Reuse, and Recycle. They are a widely recognized hierarchy of waste management and sustainability that encourages individuals and organizations to minimize waste and promote sustainability by reducing their consumption of resources, reusing products and materials whenever possible, and recycling materials that cannot be reduced or reused.

2. What is a biodegradable polymer?

A biodegradable polymer is a type of plastic that is designed to break down and decompose into natural substances over time through the action of microbes, heat, and other environmental factors. Biodegradable polymers are typically made from renewable resources, such as plant-based materials, and are designed to be more environmentally friendly than traditional petroleum-based plastics.

3. What is biodegradable degradation?

Biodegradable degradation refers to the process of breaking down and decomposing organic material into natural substances through the action of microbes, heat, and other environmental factors. This process is a natural and essential part of the earth’s ecosystem and helps to recycle nutrients and other substances in the environment.

Introduction

A dam is a man-made obstruction built across a river or underground stream to restrict the flow of water. This results in the creation of artificial lakes or reservoirs. Then, this has other uses. such as irrigation, domestic purposes, flood control, commercial purposes, aquaculture, electricity production, etc. They used bricks, clay, concrete, cement, iron riding, etc. to build their construction. Even though it provides a lot of benefits, there are some drawbacks as well. The environment of the river will be impacted when more dams are built over it. due to the abundance of aquatic life in the river. There is therefore a pressing need for a dam alternative.

Advantages of Dams

A dam has several advantages, ranging from economic to social advantages. The following is a list of benefit of a dam.

• Water storage: It can serve as a sizable water reserve that can be used for domestic, commercial, and agricultural purposes. Additionally, it has the capacity to accept extra surface water.
• Recreation: Dam’s are a point of public attraction as many leisure activities like boating, camping, swimming, etc. can be done in this area.
• Irrigation:The dam is a significant source of water for irrigation.
• Debris control: The dam has improved environmental protection by reducing the amount of trash thrown into rivers.
• Electricity production: Hydropower is a crucial source of electricity because it doesn’t produce any chemical waste. The majority of the nation’s primary source of electricity is generated from water.

Disadvantages of Dams

Dams are constructed to generate additional electricity for use by people. However, the bulk of these dams are unable to make a significant impact on the generation of power for human needs. Instead, it has certain negative repercussions on both the ecology and people as a whole. Some of them are mentioned below-

• Dam construction has an negative impact on the aquatic life that exists in the water.
• There is lots of water wastage during the process of dam construction.
• It has affected the people who live nearby as a sizable portion of land has been buried to serve as a water reservoir.
• Due to dam construction biodiversity in the water has reduced.
• There is an increased sediment accumulation
• Soil erosion has occurred in places nearby to the dams.
• There is a danger of catastrophe because by chance if the dam structure breaks it will threaten the lives of  thousands of people,
• Overflow of water in the dam may happen if more water reaches the surface by rain which might lead to flooding in the nearby areas.

Alternative solutions to Dams

Dams have a number of drawbacks since they are not the ideal solution for meeting human requirements. Therefore, finding a dam replacement is essential. Some of the alternative solutions to dams are given below-

• Concentrating on alternative energy sources-The construction of dams is a result of the rise in electricity demand; therefore, finding an effective source of energy production will lessen the danger posed by dams. Some common alternative energy sources ares nuclear power plants, thermal power plants, solar electricity, wind power, etc.
• Reuse of water: The dam provides water for numerous uses that. Therefore, locating new alternate water sources can also help to lower the number of dams. For instance, sewage water can be recycled and used again for a variety of various purposes, including industrial and agricultural ones.
• Managing flood: By reducing the water runoff we can control the flood of many rivers. Since dams play a prominent role in the prevention of floods in rivers.
• Concentrate more on the current dams: Only small a fraction of dams are used effectively. Hence,prior to building a new dam, one must pay attention to the older dams and make the best use of them.As a result, fewer dams may be constructed to bridge rivers.
• Groundwater recharge: Increased water deposition from surface water to groundwater is known as groundwater recharge. This process increases the water content below the ground level which can be used for various other purposes.

Summary

Water is a priceless resource that is essential to maintaining human life. It may be used for everything from generating electricity to drinking puropses. Consequently, a reliable water source is always going to be required. A dam is a man-made structure designed to preseve water. Nevertheless, while there are numerous benefits of dams, there are also some drawbacks. Being a man-made construction, it has a severe impact on the ecosystem around us. Therefore, a water  resource other than the dam is desperately needed. Alternative methods of dams include replenishing the groundwater table, locating alternate energy sources, etc. If appropriate measures are not taken into consideration, we could face a number of issues. And hence for this purpose new technologies must be implemented..

Frequently Asked Questions

1. Which of the dams on Earth is the oldest?
Ans: The dam Jawa, which is situated in Jordan, is the oldest dam still in use today. There are still some of this dam’s remains.

2. How long do dams last?
Ans: A dam’s lifespan is estimated to be 50 years on average. In this lifespan, it can function successfully. There are also other dams that date back far more.

3. Can a dam contaminate water?
Ans: Since dams stop the flow of water, they can accelerate the growth of any existing microbes in the water, which can render the water hazardous. The number of diseases spurred on by water pollution has been rising daily. Additionally, metallic components can also accumulate in such stagnant waters which can further harms marine life.

Introduction

An engine used to convert mechanical energy into electrical energy is an AC generator. Steam turbines, gas turbines, water turbines, and other similar devices all generate this energy. It creates a sinusoidal waveform of alternating current. Alternators are another name for AC generators. The electromagnetic induction law of Faraday is the foundation of an AC generator. According to this rule, anytime a conductor is exposed to a variety of magnetic fields, an electromotive force (EMF) is generated across it. This EMF is referred to as an induced EMF. Electromagnetic induction is the term for this phenomenon. Induced electromagnetic induction is the process by which a coil develops a potential difference as a result of changes in the magnetic flux flowing through it. Several types of AC generators, including polyphase generators, rotating field generators and spinning armature generators.

For more details watch the video of the Science Course for classes 6th, 7th, and 8th.

What is an AC Generator?

An AC generator is an engine that converts mechanical energy into electrical energy in the form of an alternating driving force. To provide a consistent magnetic field, an AC generator uses two magnet poles.

AC Generator Parts and Function

An electromagnet with two poles, the North Pole and the South Pole, is a component of an AC generator.  Below is a discussion of certain AC generator components, including the rotor, slip rings, and armature loop.

a. Field

The output voltage of an AC generator is obtained from the source using conductor loops. The field’s main function is to provide a magnetic field that will stimulate the gadget.

b. Armature

The armature coil is a coil that is part of the generator and produces output voltage. An armature coil’s job is to move electricity through the generator.

c. Prime Mover 

The primary mover of an AC generator is either an engine or a turbine. It serves as the appliance’s power supply.

d. Rotor 

A rotor is a revolving component with magnetic field spirals. It generates the necessary output voltage.

e. Stator

A stationary part holding the armature spirals is called a stator. A stator includes three different parts. They are stator frame, stator core, and armature spirals.

1. Stator frame: A frame that grips the stator core and armature spirals.
2. Stator core: There are slots in the inner part of the core that hold the armature spirals. A steel or iron is coated on the walls of the stator core to decrease the eddy current losses.
3. Armature winding: They are bounded on the stator core.

f. Slip Rings

There are two small rectangular blocks fixed with slip rings called carbon brushes. They are attached to the galvanometer.

Principle of Electric Generator

The basis of AC generators is Faraday’s law of electromagnetic induction. A current-carrying coil placed in a consistent field of force produces the driving force that is referred to as the law.

Construction and Working of an AC Generator 

An AC generator consists of a rectangular coil with two magnet poles attached to it on either side. Two rings are used to fasten the coil’s (or loop’s) perimeter. The rings are joined together with brushes. When a conductor travels in a magnetic field, an electric 

The generator induces a current in it.

Between the magnet’s poles, a rotating rectangular coil, also known as an armature, is used. The magnetic field’s vertical axis is the centre of rotation. The flux in contact with the armature changes as it rotates constantly. The alteration in flux results in the generation of an emf. As a result, the galvanometer, slip rings, and carbon brushes produce an electric current. While direct current only travels in one direction, alternating current sometimes flips direction.

The production of the AC generator shown in the above graph is described as

1. Induced EMF is zero when the coil is at point A because it moves equidistantly from the magnetic field’s curve at that point.
2. A gradient of 90o is created between the coil‘s motion and the magnetic field as it moves from point A to point B, and induced EMF is at its highest level during this time.
3. Moving the coil from A to B results in the same motion being equally far from the magnetic field and no generated EMF.
4. The induced EMF is once more at its highest when the coil is moved from C to D since its motion is antiparallel to the magnetic field and its angle is 270o.
5. The coil completes one cycle and moves equally far from the magnetic field when it moves from D to A. Induced EMF is therefore zero.

Advantages of AC Generator Over DC Generator

Category	AC Generator	DC Generator
Output Voltage	Higher Output Voltage.	It cannot generate a higher output voltage as it damages the functioning of the commutator.
Construction	Simpler construction	Construction is complicated due to a commutator.
Functioning	Works on the principle of electromagnetic induction.	DC generator functioning is more complex than an AC generator.
Maintenance	It demands less maintenance.	It demands more maintenance than an AC generator.
Cost	Cheaper	Costs higher than AC generator
Efficiency	Transmission efficiency is higher as AC reduces transmission losses.	Transmission efficiency is lower.

You can also read “What is AC Voltage Capacitor?” for explanation of AC voltage.

Summary

A generator is an engine that changes one type of energy into another. Large currents are produced by electric generators for usage in industrial and domestic applications. There are two different kinds of electric generators: DC generators, which convert mechanical energy into direct current. A generator of alternating current that converts mechanical energy. On the Faraday law of EMI theory, an AC generator was placed. In an AC generator, the flux in contact with the armature varies as it rotates continuously. The shift in flux causes an emf to be generated. As a result, the galvanometer, slip rings, and carbon brushes produce an electric current. As an AC generator produces higher output voltage, it is easier to build, requires less maintenance, is more efficient, and is less expensive than a DC generator. Large currents are produced by electric generators for usage in industrial and domestic applications.

Frequently Asked Questions 

1. Can we Generate EMF without Rotating the Coil in an AC Generator? Explain.

Ans: Yes, emf may be produced without the coil revolving. If the armature is made to move at a velocity perpendicular to the magnetic field, Emf can also be produced.

2. What is the reason for Heat Loss in the Generator?

Ans: Reasons for the heat loss in the generator can be, (a) generation of the by-products like carbon dioxide, and molecular friction, which can reduce the efficiency. The heat loss hinders the efficiency of the generator. So, the efficiency is never 100%. 

3. What is the Driving Force?

Ans: Induced emf is also termed as the driving force and can be expressed as, 

                                                      ε = N B Aωsinωt

where N is the number of turns in the coil, B is a magnetic field, A is an area, ω is the angular velocity

So, in an AC generator, the induced emf is proportional to the applied magnetic field.

4. Give examples of DC Sources.

Ans: The electrical appliances like radios, televisions, and solar panels. DC only travels in one direction and lacks any polarity.

Introduction

When people think of algae, they typically picture slimy, green films that grow in still waterways (freshwater and marine). Depending on the species, an Alga may range in size from microscopic to macroscopic and up to a few feet long. Algae are the primary source of atmospheric oxygen that supports many life forms on earth while being blamed for ruining the beauty of transparent waters. The term phycology refers to the study of algae, and phycologists are those who conduct in-depth research on the organisms.

What is Algae?

Algae are cosmopolitan autotrophic eukaryotes having one or more cells that are capable of photosynthetic activity. Organelles like chloroplasts, mitochondria, and the nucleus are membrane-bound in algal cells. 

A common mistake students make is memorising Science or a process without understanding the concept behind it. Check out online study options are a great way to clear the science concepts you need. Watch the related video of these Science Concepts.

Examples of Algae

Some well-known algae include euglenoids, diatoms, kelps, Laminaria, Spirogyra, Volvox, Chara, Fucus, Micromonas, Noctaluca, Chilomonas, Gracilaria, and Chlamydomonas.

Characteristics of Algae

Algae can be multicellular or unicellular. They can also be microscopic as diatoms or large and leafy like kelp. They possess certain qualities that are essential for surviving in predetermined living circumstances.

Habitat: 

• The majority of algal species are found in freshwater and marine aquatic habitats. 
• Different types of water and temperatures allow algae to survive. 
• They can also grow on submerged surfaces and damp rocks. 

Morphology:

• Unlike plants, algae have a simple form. Unicellular algae can organise themselves into filaments or colonies and are either motile or non-motile.
• Kelp-like multicellular algae contain body features that are intended to serve particular purposes.

                                                

Interaction with Environment

Some algae can survive on their own (suspended in water or attached to the substrate), while some species coexist harmoniously with sponges, coral reefs, and fungi. 

Mode of nutrition:

• Chlorophyll is a pigment found in the majority of algae, which are photoautotrophs (photosynthetic pigment).
• The facultative and obligate heterotrophic algae are the only real exceptions. They need carbon substrates from their environment to survive. Some people think that algae exhibit mixotrophy (autotrophy and heterotrophy).

Reproduction

• Mitosis and fragmentation are used in vegetative reproduction. In fragmentation, the damaged component regenerates into a whole body. 
• Spore formation is the means of asexual reproduction. Mature cells divide and produce spores in their cytoplasm. Upon the emergence of favourable conditions, spores transform into new individuals. 
• Sexual reproduction is continued by gametes. Zygotes are created when male and female gametes combine. Female gametes can occasionally grow right into zygotes. This process is called parthenogenesis.

Classification of Algae

Based on their colours, distinct phyla of algae are subdivided. 

• Chlorophyta: Chlorophyll a and b, as well as carotenes, are the pigments found in chlorophyta (green algae). They can be found in colonies, multicellular forms, or unicellular forms. 
• Rhodophyta: Chlorophylls a and d, as well as phycoerythrin and phycocyanin, are the pigments found in Rhodophyta (red algae). They have a crimson appearance because of the phycoerythrin pigment. 
• Phaeophyta: Brown algae, or Phaeophyta, are pigmented with fucoxanthin and chlorophyll a and c. This category primarily includes kelps and seaweeds. 

Types of Algae

Depending on where they live, there are several forms of algae. 

• Cryophilic algae: Grow in snow and ice.
• Thermophilic algae: Grow in hot climates close to hot springs.
• Epizoic algae: Live on the bodies of aquatic creatures like turtles. 
• Edaphic algae: Grow in soil. 
• Epilithic algae: Grow on rocks. 
• Endolithic algae: Inhabit coral reefs. Some call it a symbiotic relationship.
• Corticolous algae: Grow on moist tree trunks.

Chemical Composition of Algae

They contain a variety of pigments, including fucoxanthin, carotenes, phycocyanins, and chlorophyll. Algae have significantly variable cell wall compositions. Cellulose, alginate, carrageenan, agarose, and glycoproteins, including galactans and mannans, are all parts of an algae’s cell wall. Other biomolecules found in algae include lipids, proteins, carbohydrates, nucleic acids (DNA since eukaryotes), and nucleic acids.

Difference between Normal Plants and Algae

Algae, like many sophisticated multicellular plants, use photosynthesis, which explains why chlorophyll is present. They don’t have genuine stems, leaves, or a clearly defined vascular system, which makes them different from plants.

Importance and Uses of Algae 

• They provide between 30 and 50 percent of the oxygen needed for other life forms on Earth. 
• Due to their abilities to gel, become colloidal, and create emulsions, red and brown algal extracts such as alginates, agar, and carrageenans are in high demand in the food sector. 
• Algae are quite sensitive to the condition of the water (pH and composition). They serve as bioindicators of environmental toxicity. 
• From algae that formerly inhabited sea floors, natural gas and crude oil are created. Nowadays, biofuel made from algae is more and more widespread.

Difference between Algae and Fungi

• Fungi are saprophytes. They depend on dead and decaying organic material for nutrients while algae are autotrophs. 
• Algae are very different from fungi, which have chitinous cell walls and no chlorophyll. Both, however, exist as lichens and have a symbiotic connection.
• Algae (often green algae) receive protection from fungi, and fungi receive nutrition from algae.

The Life Cycle of Algae 

• Haplontic life cycle: The plant is haploid throughout. A diploid zygote is created when gametes (which are created by mitosis) combine. The zygote proceeds through meiosis and produces meiospores, which grow into young algae.
• Diplontic life cycle: The body of the sporophytic plant is diploid. The zygote is created by fusing haploid gametes.
• Diplohaplontic life cycle: In the lifetime, haploid and diploid stages are equally dominant. While diploid sporophytes reproduce asexually, haploid gametophytes proliferate sexually.
• Triphasic life cycle: The life cycle alternates between three generations.

• Gametophyte is the dominant stage in a haplontic system. There are two haploid and one diploid generation in the life cycle. 
• Sporophyte, the dominant stage in a diplobiontic organism, There are two diploid and one haploid generation in the life cycle.

Summary

Algae are autotrophic eukaryotes that have one or more cells that are capable of photosynthetic activity. Algae can also be microscopic multicellular (likely leaf-like Giant kelps or unicellular. Chlorophyll is a pigment found in the majority of algae, which are photoautotrophs. Chlorophyll a and b, as well as carotenes, are the pigments found in chlorophyta. Algae are quite sensitive to the condition of the water. They serve as bioindicators of environmental toxicity.

Frequently Asked Questions 

1. Are there Roots in Algae?
Ans. Algae don’t have actual roots. Algae have hold-fast organs in place of roots, which serve as anchors and keep immobile algae attached to a solid substrate.

2. Describe Kelp Forests.
Ans. Brown multicellular algae make up kelp. They live in shallow waters close to the beach. Several small invertebrates and fish breed in dense, thick-grown kelp. Carnivores such as seals and sea lions eat kelp by diving into it, forming an ecosystem.

3. Are Humans Harmed by Algae?
Ans. Algae pose no threat. Some algae create toxic substances that are dangerous to people. Fever, diarrhoea, and skin rashes are the results of direct exposure to these poisons.

4. Are Algae Capable of Producing Biofuel?
Ans. Following numerous stages, the energy-dense oil produced from algae is transformed into different types of fuel. Each species has a different process.

5. What Occurs if the huge Kelp is Removed?
Ans. Algae with their many cells can regenerate. If the environment is right, the damaged component can regenerate into a new body. If not consumed by herbivores, it otherwise deteriorates and decomposes.

Introduction

A dam is a physical structure that slows or restricts the flow of subsurface or surface water. Dams build reservoirs that serve multiple purposes, including flood control, irrigation, human consumption, industrial use, aquaculture, and navigability. Although they are more frequently erected on rivers, dams can be constructed anywhere. They may also be built on streams and estuaries.

What is a Dam?

A dam is a sizable, barrier-like structure that is erected across a body of flowing water. Water is held back and stored for later use because of construction. A reservoir is a term used to describe the vast amount of water storage created on the upstream side of a river when it is prevented from flowing by a barrier. Floodgates on dams can be opened or closed to allow only a small flow for human use.

During floods, gates also enable the release of extra water from the reservoir side. A surplus of water collects on the reservoir side of a river when it floods. To let surplus water out, the floodgates are slowly opened. Dams are primarily built for this reason.

For more help, you can Refer to lesson 16 – Water in Science Class 7. Checkout the video Lesson for a better understanding

Uses of Dams

• Irrigation: In recent years, irrigation for crops has primarily been provided by dams. Rainfall in tropical nations like India is only experienced for a portion of the year. However, agriculture is a year-round industry that uses water for growth, depending on the stage of growth. While others, like rice and sugarcane, require excessive amounts of water. Agriculture was made possible by irrigation, even in remote areas with low subterranean water levels.
• Electricity: The floodgates are opened, allowing the reservoir’s water which is already under high pressure to pass through the turbine that powers the generator. A turbine transforms the kinetic energy of water into mechanical energy, which is then transformed into electrical energy by a generator.
• Reservoirs are a great place for recreation. Many reservoirs provide the local people with camping, boating, and fishing facilities.

Advantages of Dams

• Hydroelectric power, which is produced by dams, is independent of all fossil fuels. As a result, hydroelectricity is a source of energy that is constantly replenishing and can be used. With a growing population comes a rising need for energy. One of the safest methods to address the energy situation is using hydroelectric electricity.
• A reservoir maintains a sizable water reserve that is mostly used to store fresh water that can be used later in times of water scarcity.
• You can irrigate with the reservoir water. Crop plants can be effectively watered across long distances. Food is produced on the irrigated farmlands. Demands for drinking water are alarmingly rising along with population growth.
• Floods are prevented by dams, which redirect water flow. Numerous lives are saved every time water is slowly released from reservoirs through floodgates, and property damage is also avoided. 
• A reservoir is a gathering place for many aquatic animals, including fish and turtles. When dams are built, a river that is already flowing becomes a lake. It becomes a lake environment when freshwater fish and turtle species seize the opportunity to multiply.

Disadvantages of Dams

• To create a sturdy basement and reservoir, large layers of dirt must be dug out during the dam’s construction. The earth’s topography is harmed by this. Because of this, earthquakes happen more frequently. However, effective engineering, design, and planning can stop such destruction. 
• Dams are substantial, concrete buildings. They are not built economically. 
• Dam construction necessitates a vast area. It is necessary to move the local farmers and residents to the area. Their social and economic lives are affected, and there are long-term repercussions.
• In addition to displacing people, the natural habitat is also greatly disturbed. Concerns about the flora impacted by dam construction are mostly focused on deforestation and the loss of agriculturally productive land. 
• Natural wildlife that lives in the dam region is also out of control and occasionally even poses a threat to its population. To maintain their populations, breeding grounds and nesting locations are crucial. When other factors perturb these areas, their population changes. 
• Bird species are disturbed, in addition to terrestrial and aquatic species. 
• Fish living in freshwaters are the primary food source for migratory birds that nest on riverbanks. 
• Migratory birds lose their feed and are prevented from reproducing as they do throughout the year due to the drastic shift in aquatic life caused by dam building.
• The groundwater table in the surrounding areas is decreased as a result of deepening the riverbed to create reservoirs. This has a significant negative influence on nearby, naturally occurring vegetation.

Summary

A dam is a physical obstruction that slows or restricts the flow of subsurface or surface water. Floodgates on dams can be opened or closed to allow only a small flow for human use. In recent years, irrigation for crops has primarily been provided by dams.  A reservoir maintains a sizable water reserve that is mostly used to store fresh water that can be used later in times of water scarcity. Dams are substantial, concrete buildings. They are not built economically.

Frequently Asked Questions 

1. Do Dams Last Forever?
Ans. A dam may be built in around ten years, and its lifespan is about one hundred years. Certain mechanical components, including motors and gates, need to be changed after a dam has been in place for 50 years. However, operational dams will undergo routine inspections. When necessary, all repairs and maintenance will be carried out right away.

2. Can we Rely Solely on Hydroelectricity to Provide our Electricity?
Ans. A renewable energy source is a hydroelectricity. Since the dam-related operation does not disrupt the water cycle, the claim that water will not run out is valid. The problem is that rivers and streams are the only sources of flowing water that dams may use. Hydroelectric power cannot be the only source of sustainably produced energy.

3. What Connection does a Dam have to Greenhouse Gases?
Ans. Large expanses of vegetation are flooded when a dam is built, submerging numerous trees. Low oxygen levels can be found near the bottom of stagnant waters in reservoirs. The reservoir’s lower layers, which are abundant in biomass, effectively release methane into the atmosphere as it breaks down.

4. What Advantages do Dams Offer to Farmers?
Ans. Large amounts of water are stored in reservoirs where they can be irrigated for use in agriculture. Croplands can also be effectively irrigated in semiarid areas far from the riverbed. Rainfall is not necessary for farmers to be able to cultivate.

An Introduction to Acids and Bases

Acids are substances with a pH below 7 that release hydrogen ions or a proton when combined in an aqueous solution. The dissociable protons or hydrogen groups, also known as acidic hydrogen, that easily split apart in solution or the presence of bases are the main constituent of these acids.

Bases are substances that yield hydroxyl ions when combined with water in an aqueous solution when combined with water in an aqueous solution, yield hydroxyl ions. Their pH is higher than 7. Therefore, a base has a basic group that separates in an aqueous media or a dissociable hydroxyl group. Bases may also be referred to as substances that are hydrogen acceptors because they are substances that can either receive or accept hydrogen ions.

The pH Scale

The pH scale determines the strength of an acid or base by specifying the degree of dissociation. A strong acid or base dissociates in water, producing massive amounts of hydrogen or hydroxyl ions. A dissociation constant is used to calculate an acid or base’s dissociation of an acid or base.

Strong Acid

Since extremely acidic hydrogens are extremely acidic hydrogens present, strong acids HA has a high dissociation. Commonly, these hydrogens are attached to extremely electronegative groups (often halogens like chlorine, fluorine, and iodine). 

Low pH is found in strong acids. The amount of hydrogen ions in a solution is related to the pH. The negative logarithm of the concentration of hydrogen ions is the mathematical representation of pH.

\[pH =  – \log [{H^ + }]\]

The dissociation constant of acids, a parameter \({K_a}\), is used to account for the degree of dissociation. Increased dissociation and hence higher acidity are indicated by a high \({K_a}\) value. 

In chemistry, the \(p{K_a}\) value—the negative logarithm of \({K_a}\)—which is the logarithmic acid dissociation constant—is taken into account for convenience. Therefore, stronger acids will have a low pKa value and a high acid dissociation constant \({K_a}\) value, and vice versa.

\[p{K_a} =  – \log {K_a}\]

 Examples of Strong Acids

Strong Acids	Formula
Hydrochloric Acid	HCl
Sulphuric Acid	H2SO4
Nitric Acid	HNO3

Strong Base

Strong bases NaOH are substances that split apart in solution to form high quantities of hydroxyl ions. In addition, bases have the potential to be strong proton acceptors, which means that they could grab a proton from the water molecule \({H_2}O\) in an aqueous solution to produce an \(O{H^ – }\) ion.

\[NaOH \to N{a^ + }(aq) + O{H^ – }(aq)\]

The base dissociation constant Kb describes the level of dissociation in the case of bases. Stronger bases are associated with lower values of the logarithmic base dissociation constant, or, which is equivalent to \(p{K_a}\).

\[p{K_b} =  – \log {K_b}\]

Similar to pH, the concentration of hydroxyl ions is related to pOH. A strong base that supplied a lot of hydroxyl ions would have low pOH because the concentration of hydroxyl ions is a negative logarithm.

\[pOH =  – \log [O{H^ – }]\]

The equation pH + pOH = 14 relates pH and pOH in an aqueous solution. If one is known, the other can be used to compute either pH or pOH.

Strong bases commonly have a pH range of 13–14.

Examples of Strong Bases

Strong Bases	Formula
Calcium Hydroxide	Ca(OH)2
Sodium Hydroxide	NaOH
Potassium Hydroxide	KOH
Lithium Hydroxide	LiOH

Summary

Strong acids and bases are the subjects of this article, which also examines how strong acids or basic solutions are based on their pH. Strong acids and strong bases have a high degree of dissociation. Strong acids and bases dissociate in solution, releasing a lot of proton and hydroxyl ions. Strong bases have high pH, whereas strong acids have low pH. 

Frequently Asked Questions

1. What is the Body’s pH?

Ans. The pH of human blood ranges from 7.35 to 7.45, making it very slightly alkaline. With a pH range of 1.5 to 3.5, the human stomach is the most acidic organ in the body. To break down food for digestion and remove any unwanted microorganisms, the stomach is kept at a low pH.

2. What are the Main Differences between a Strong Acid and a Weak Acid?

Strong Acids	Weak Acids
When exposed to water, strong acids completely dissociate into their ions.	In an aqueous solution, weak acids are molecules that partially dissociate into ions.
A strong acid solution has a very low pH.	A weak acid solution has a pH of 3-5.
It releases all the H+ ions to the solution.	Partially releases all H+ ions to enter the solution.

3. What are the Main Differences between a Strong Base and a Weak Base?

Strong Bases	Weak Bases
In a solution, a strong base can completely dissociate into its cation and hydroxyl ion.	A weak base partially dissociates into its hydroxyl ion and cation, resulting in an equilibrium state.

Introduction

The topmost layer of the earth is called soil, and it is made up of several elements. Environmental elements like water, wind, temperature, and even living things usually have an impact on them. One type of soil may not have the same physical or chemical properties as another. The soil is now inhabited by microorganisms like bacteria, algae, fungi, and actinomycetes that fix nitrogen, decompose organic matter, transport vital nutrients, and improve the texture of the soil. High-yielding crops in agriculture depend on the texture, composition, and environmental tolerance of the soil. Consequently, the soil is first prepped before being used for improved harvesting.

What is Soil?

A complex material called soil develops on the earth’s surface. It emerged through the disintegration of rocks. By their porosity, aeration, and water-retention ability, they act as a medium for the growth of plants.

Let our expert Guru be your guide toward improving your grades and reaching your highest potential.l. Delve into Science lessons for class 7th by 88Guru.

Types of Soil

Based on its texture and composition, the soil is divided into different categories.

Clay soil:

• Compared to other soil types with a composition of very small particles, clay soil stands out for having particular qualities. 
• It is referred to as heavy soil because the soil particles are firmly packed and there are few or no air spaces between them. 
• It has trouble allowing air and humidity to enter the soil yet is effective at holding a lot of water. 
• Although clay is sticky when wet, it dries out when water vapour escapes from the ground.

Sandy soil:

• Sandy soil is hot and dry because it has a large proportion of sand and little clay. 
• It can be created through the fracturing of rocks. 
• When it rains heavily, the earth can quickly absorb water, which benefits the drainage system. 
• The lack of proper water retention and poor nutrient availability make the soil unsuitable for plant growth.

Loamy soil:

• Silt, clay, sand, and organic matter that has already decomposed make up loamy soil, which has a dark colour. 
• Because the soil’s particles are dispersed, air can easily penetrate it. 
• It works well for plant growth since clay and sand both have beneficial properties.

Silt:

• The particle size of such soil is medium. 
• Although the soil is fertile and smooth, it has few nutrients. 
• It is utilized for drainage since it effectively traps water.

Which Soil is Suitable for Agriculture?

Crops can only be grown in a particular soil if it meets certain criteria, including aeration, fertility, and crop type. Generally speaking, it differs amongst crops. To provide appropriate nutrients and maintain the water, the loam soil is made up of sand, silt, and clay. In this way, it is regarded as appropriate soil for farming.

Components of Soil

• From one place to another, the soil’s precise makeup varies. Minerals, water, and organic and inorganic substances make up the major volume of the soil. 
• Generally speaking, the abiotic (non-living) components are made up of about 45% air, 25% water, 25% minerals, and 5% organic stuff.

Preparation of Soil

Before planting, the soil is prepared to ensure that the region is suitable for farming. The proper growth of crops might benefit from soil preparation. The soil preparation process involves a variety of tools.

Tools Involved in Soil Preparation

Plough:

        Plough is dragged by two bullocks and is composed of wood or iron. The pieces are as follows: 

• Shovel shaft (a long batten of wood). 
• Ploughshare (heavy triangular metal item linked to one pole of shaft) (heavy triangular metal piece connected to one pole of shaft). 
• Beam (the other pole of the shaft is connected to the stand on the necks of bulls).

Hoe: 

• Hoe is used to break up the soil and remove overgrowth. 
• Bulls drag a long wooden pole with heavy metal attached to it to loosen the dirt.

Cultivator:

• Both labourers and cultivators plough the ground. 
• The main ways that tractors are beneficial are by eliminating physical labour and saving time.

Different Steps Involved in the Preparation of Soil

The process of preparing soil involves these three steps: 

Ploughing: 

• It is the process of agitating and moving the soil to bring nutrient-rich soil to the surface. 
• It is an essential phase in agriculture, and iron or wood has been used to apply it. 
• Bullocks or driven cultivators pull the plough. 

Leveling: 

• Due to the numerous huge lumps in the region that was ploughed, it is crucial to level the ground before beginning cultivation. 
• A leveler is a tool with a board made of metal or wood that is used to level the soil.

Manuring:

• Manure is decomposed organic matter that is used as fertilizer to improve the quality and growth of crops. 
• Manure is utilized to replenish the soil with nutrients necessary for the successful growth of crops.

Importance of Preparation of Soil

• By preparing the soil in a way that safeguards the crops from irritants and weeds, it is possible to meet the needs of crops, including those for sufficient water, minerals, oxygen, nutrients, and solar exposure. 
• Ploughing helps cultivators get nutrient-rich soil on the top, promote soil aeration, and get rid of unwelcome weed development. 
• Crops must be properly mowed to ensure a superior harvest.

For more help, you can Refer to Lesson 9 – Story of soil in Science Class 7. Checkout the video Lesson for a better understanding.

Summary

A complex material called soil develops on the earth’s surface. It emerged through the disintegration of rocks. Based on its texture and composition, the soil is divided into different categories, such as clay, sandy, silty, and loamy soil. Crops can only be grown in a particular soil if it meets certain criteria, including aeration, fertility, and crop type. Ploughing helps cultivators get nutrient-rich soil on top, promote soil aeration, and get rid of unwelcome weed development.

Frequently Asked Questions

1. What characteristics of Soil make it Appropriate for Farming?

Ans. A good supply of nutrients and oxygen, the ability to hold onto water, and weather tolerance are all characteristics of soil that make it suited for agricultural use.

2. What makes up Soil?

Ans. 45% of air, 25% of water, 25% of minerals, and 5% of organic matter make up soil. Organic matter is the byproduct of plants and animals that have decomposed.

3. What is Clay Soil?

Ans. Compared to other soil types with a composition of very small particles, clay soil stands out for having particular qualities. It is referred to as “heavy soil” because the soil particles are firmly packed and there are few or no air spaces between them.

4. Define Ploughing and what are the Components of the Plough.

Ans. Loosening and turning the soil is done through ploughing. A plough is a farming implement made up of a beam, ploughshare, and shaft.

5. What kind of Soil can hold a Significant Amount of Water, and Why?

Ans. Clay soil can store a huge quantity of water. It is referred to as “heavy soil” because the soil particles are firmly packed and there are few or no air spaces between them. It has trouble allowing air and humidity to enter the soil yet is effective at holding a lot of water.

Introduction

The matter may be found on Earth in three different states: solid, liquid, or gaseous. Every matter is composed of incredibly tiny building components called atoms and molecules. These particles in a solid are strongly attracted to each other and vibrate in place without passing by each other. Despite not being as strong as it is in a solid, there is still an attraction between the particles in a liquid. The proximity and frequent movement of the particles in a liquid allow them to slip past one another. There is only a weak attraction between gaseous particles. They are continually moving and spread out compared to the particles in a solid or liquid. Here the particles do not interact when they collide; they just strike and bounce off of one another. This article provides a thorough understanding of the concept of matter of space between particles and attraction between the matter particles with specific instances.

Particles have Space between Them

Let’s observe a small activity to determine whether the particles are separated from one another; this is explained below.

Experiment

Take a beaker filled with 100 ml of water and then add 20 gm of sodium chloride (table salt) into it. Make sure to swirl the water with a glass stirring rod until all the salt has completely dissolved. The salt will dissolve, and then we will get a solution.

Observations

It has been observed that even after 20 gm of salt has been dissolved in 100 ml of water, the level of the water doesn’t actually rise. This displays how free and interparticle space-containing water atoms are. This area is known as the interparticle or intermolecular space. In this interparticle area, the salt granules that were scattered have settled.

Particles of Matter are Constantly Moving at Random

Diffusion and Brownian motion demonstrate that particles are moving.

Diffusion

A material will mix and disperse with another substance through a process called diffusion while its particles are in motion. To homogenize the mixture, this process is repeated. For instance, the ink diffuses in the water as a result of the random movement of water and ink particles. Ink migrates from areas of higher concentration to regions of lower concentration at a pace that is inversely associated with the liquid diffusion rate of the ink. Diffusion occurs in liquids, solids, and gases, however, it occurs more rapidly in gases and less efficiently in solids.

Brownian Motion

Brownian suspended several pollen grains in water and then examined them under a microscope. He saw that the pollen grains were moving in a zigzag pattern. The movement is significantly more evident when the water is warmed. Water is made up of randomly migrating atoms. As a result, the moving atoms frequently strike the pollen grains, causing them to migrate. As an example of Brownian motion, the pollen grains are travelling in this manner.

Particles of Matter Attract Each Other

A force acting on the particles of matter holds them together. Some substances crumble into powder, while others form tiny crystals, and still, others are challenging to separate. The strength of the force of attraction varies from one type of substance to another, depending on that substance. This is done so that the force of attraction between the particles can keep the particles inside them. This interparticle force of attraction exists in all substances that cause the attraction of particles. Therefore, to break objects, we must defeat the force of attraction. A varying amount of strength is necessary depending on the chemical.

Examples show that breaking a chalk is easier than breaking a nail. This illustrates how 

various material particles have varied levels of attraction. The attraction between particles of the same material is referred to as “cohesion.”

Summary

The particles are separated by a certain amount of space, in which the gaseous form of matter has the largest inter-particle space among the three states of matter. Interestingly, the interparticle gaps that exist in various types of matter are what give rise to the three states of matter, and therefore the density of different states of matter increases from a gas to a solid state (for example water vapor to water and then ice). 

Frequently Asked Questions

1. Define Matter.

Ans: A component that is made up of several types of particles, takes up space, and has motion is referred to as “matter.”

2. What Constitutes Matter?

Ans: Matter is made up of atoms, which are made up of electrons, protons, and neutrons.

3. How to Develop the Model of Particles of Gas and Liquid?

Ans: By compressing a flexible plastic container with a balloon on top, we can imitate the gas particles. We can also try to squeeze a water-filled container as part of their modelling of liquid particles.