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ScienceClass 10CBSE

1. Which part of the solar cooker is responsible for green house effect? (a) Coating with black colour inside the box (b) Mirror (c) Glass sheet Outer cover of the solar cooker

Soln: Answer is (c) Glass sheet Explanation: Green house effect is due the trapping of heat by the atmosphere. Heat is produced is due to presence of green house gases like CO2, SO2. In Solar cooker same thing happens. Solar energy trapped is reflected by the glass sheet which make the food cook.

ScienceClass 10CBSE

1. The major problem in harnessing nuclear energy is how to (a) split nuclei? (b) sustain the reaction? (c) dispose off spent fuel safely? (d) convert nuclear energy into electrical energy?

Soln: Answer is (c) dispose off spent fuel safely? Explanation: Nuclear plants produces highly radioactive material. This if released to the environment they pose major threat to living organisms. Hence, disposing the spent fuel safely is a major problem in harnessing nuclear energy.

ScienceClass 10CBSE

1. Ocean thermal energy is due to (a) energy stored by waves in the ocean (b) temperature difference at different levels in the ocean (c) pressure difference at different levels in the ocean tides arising out in the ocean

Answer is (b) temperature difference at different levels in the ocean Explanation: Energy from surface is used to boil volatile liquid. Vapors from these are utilized to turn the turbine.

ScienceClass 10CBSE

1. Which one of the following forms of energy leads to least environmental pollution in the process of its harnessing and utilisation? (a) Nuclear energy (b) Thermal energy (c) Solar energy Geothermal energy

Answer is (c) Solar energy Explanation: In nuclear energy metals like uranium are used which releases harmful rays than can affect the living organisms. In Thermal energy coal is used which releases Sulphur and Carbon-di-oxide and causes air pollution. In the case of geothermal energy the energy is absorbed by the pressure by the heat from the core which can sometimes be extremely hot and dangerous.

ScienceClass 10CBSE

1. Which is the ultimate source of energy? (a) Water (b) Sun (c) Uranium Fossil fuels

Soln: Answer is (b) Sun Explanation: Plants produce food by using solar energy. Fossil fuels are produced from dead plants. Hence Sunlight is the source of all energy either directly or indirectly.

ScienceClass 10CBSE

1. In a hydro power plant (a) Potential energy possessed by stored water is converted into electricity (b) Kinetic energy possessed by stored water is converted into potential energy (c) Electricity is extracted from water Water is converted into steam to produce electricity

Soln: Answer is (a) Potential energy possessed by stored water is converted into electricity . Explanation: Water stored in dams possess potential energy. When it is released it possess potential energy which is used to turn the turbines. Turbines produces electricity.

ScienceClass 10CBSE

1. Fuel used in thermal power plants is (a) water (b) uranium (c) biomass fossil fuels

Soln: Answer is (d) fossil fuels Explanation: Coal is the major fossil fuel used in thermal power plants. Along with coal natural gas and petroleum are also used.

ScienceClass 10CBSE

1. Acid rain happens because (a) sun leads to heating of upper layer of atmosphere (b) burning of fossil fuels release oxides of carbon, nitrogen and sulphur in the atmosphere (c) electrical charges are produced due to friction amongst clouds earth atmosphere contains acids

Soln: Answer is (b) burning of fossil fuels release oxides of carbon, nitrogen and sulphur in the atmosphere Explanation: Acid rain happens when rain water mixes with oxides of Carbon, Nitrogen and Sulphur in the atmosphere.

ScienceClass 10CBSE

1. Which of the following is a non-renewable source of energy? (a) Wood (b) Sun (c) Fossil fuels Wind

Soln: Answer is (b) Sun

ScienceClass 10CBSE

Explain some harmful effects of agricultural practices on the environment.

Soln: Following are the harmful effects of agricultural practices on the environment Soil degradation Extensive cropping causes loss of soil fertility. Also, over the time it can lead to soil erosion and finally to desertification. Pollution Use of synthetic fertilisers and pesticides leads to soil, water and air pollution. • Water shortage Excess use of ground water for agriculture lowers the water level. This results in acute water shortage at many places. • Bio-magnification The chemical pesticides, being non-biodegradable accumulate in organisms in increasing amounts at each trophic level. Deforestation Indiscriminate cutting of trees for agriculture has resulted in loss of habitat for wildlife. Thus, it also causes damage to natural ecosystem.

ScienceClass 10CBSE

1.      What are the by-products of fertiliser industries? How do they affect the environment?

Soln: The most common byproduct of fertilizer industries are oxides of nitrogen and sulphur. They pass into the atmosphere and spread to all nearby places. The gases have a corrosive effect on several items besides being harmful to living beings. They also give rise to acid rain. Acid rain is highly destructive to forests, crops and aquatic biota. Oxides of Nitrogen and Sulphur are the most common by-product of fertilizer industries. These oxides pass into the atmosphere and spread to all nearby places. Sulphur and nitrogen oxides have a corrosive effect on several items besides being harmful to living beings. Sulphur oxides lead to acid rain which causes harms to forests, crops and aquatic biota.

ScienceClass 10CBSE

1.      Suggest suitable mechanism (s) for waste management in fertiliser industries.

Soln: To manage waste in fgertiliser industry following steps to be taken. For control of gaseous pollutants combustion equipments are used which can be oxidised. The pollutants are exposed to a high temperature in the process. Air pollutants, such as certain gases and vapour and inflammable compounds are controlled through the use' of adsorption equipments. Adsorption is a surface phenomenon and it needs the presence of a large solid surface Toxic and odoriferous compounds are efficiently removed by this process. Three options available for controlling the effluents are: Control can take place at the point of generation within the Waste water can be pre-treated for discharge to municipal treatment Waste water can be treated completely at the factory and either reused or discharged directly for receiving

ScienceClass 10CBSE

1. Name the wastes which are generated in your house daily. What measures would you take for their disposal?

Soln: Wastes generated in our house daily are as follows Kitchen wastes Paper wastes like newspapers, bags, envelopes Plastic bags Vegetable/fruit peels/rind Measures for disposal Measures to take to dispose house waste are Segregation of biodegradable and non-biodegradable Safe disposal of plastic Vegetable/fruit peels can be placed near trees/plants, which on decomposition will enrich the soil with Give paper wastes for Prepare a compost pit for kitchen

ScienceClass 10CBSE

1.      Give two differences between food chain and food web.

Soln: Food Chain Food web The food chain is the straight and single pathway for the flow of energy in an ecosystem, through different species of organisms. Food web is defined as the convoluted or complicated pathway of an ecosystem consist of numerous food chains of the different trophic level, through which the energy flow. Food chain is hypothetical situation Food web is a real life situation. Members of higher trophic level feed on single type of organism of lower trophic level Members of higher trophic level can feed upon organisms of the lower trophic levels of other food chain.

ScienceClass 10CBSE

Suggest any four activities in daily life which are eco-friendly

Soln: Activities in daily life which are eco-friendly are as follows Using of bicycles and electrical bikes instead of vehicles run by fossil Avoid using plastic bas, instead we can use bags made of clothes and Plant trees in our surroundings Stop usage of old items and recycle

ScienceClass 10CBSE

1.      What are decomposers? What will be the consequence of their absence in an ecosystem?

Microorganisms, comprising bacteria and fungi, break-down the dead remains and waste products of organisms. These microorganisms are the decomposers as they break-down the complex organic substances into simple inorganic substances that go into the soil and are used up once more by the plants. If decomposers are absent in the ecosystem recycling of material in the biosphere will not take place which would lead to accumulation of dead plants and animals in the environment. Additionally, the environment would be finally devoid of all its resources which are needed to maintain and sustain life.

ScienceClass 10CBSE

1.      We do not clean ponds or lakes, but an aquarium needs to be cleaned. Why?

Soln: An aquarium is an artificial ecosystem which is incomplete ecosystem when compared to pond or lake which is natural and complete ecosystem.

ScienceClass 10CBSE

1. Select the mis-matched pair in the following and correct it. (a) Biomagnification — Accumulation of chemicals at the successive trophic levels of a food chain (b) Ecosystem — Biotic components of environment (c) Aquarium — A man-made ecosystem Parasites — Organisms which obtain food from other living organisms

Soln: Biomagnification — Accumulation of chemicals at the successive trophic levels of a food chain Ecosystem — Biotic components of environment Aquarium — A man-made ecosystem Parasites — Organisms which obtain food from other living organisms Soln: Answer is (b) Ecosystem — Biotic components of environment Both biotic and abiotic components of environment constitute an ecosystem.

ScienceClass 10CBSE

1.      Explain the role of decomposers in the environment?

Soln: Decomposers breakdown dead and decaying living matter and helps in the nutrient recycling. This will clean the environment by removing dead material.

ScienceClass 10CBSE

1. If a grass hopper is eaten by a frog, then the energy transfer will be from (a) producer to decomposer (b) producer to primary consumer (c) primary consumer to secondary consumer secondary consumer to primary consumer

Soln: Answer is (c) primary consumer to secondary consumer Explanation: Grass hopper is a primary consumer because it feed on grass. If grasshopper is getting eaten by frog. Frog will be secondary consumer.

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