Explore topic-wise InterviewSolutions in Current Affairs.

Correct option is D) (i), (iii) and (iv)

Coal tar is a mixture of about 200 substances. It is a black, thick liquid with unpleasant smell. Synthetic dyes, drugs, perfumes, plastics and paints. Naphthalene balls used to repel moths and other insects are also obtained from coal tar.

C. water 

Water is an inexhaustible natural resource because it is available abundantly in nature.

B) 1 – e, 2 – c, 3 – a, 4 – b, 5 – d

The resources which are unlimited in nature and not likely to be exhausted by human activities are called inexhaustible resources, e.g. Solar energy, wind energy, tidal energy.

B. natural gas 

Natural gas is a fossil fuel other than coal and petroleum. Petroleum can be extracted with giant drilling machines. The layer containing petroleum oil and natural gas is above that of water.

1. If we see the history of petroleum production, from 1859 to 1969, the total production of oil was 227 billion barrels. 

2. 50% of this total was produced during the first 100 years, while the next 50% was extracted in just ten years.

3. Today our consumption rate of oil is far excess that of the rate of its formation. 

4. Earth take more than one thousand years to form the oil that we consume in one day. 

5. By about 2015, we would have consumed half of the total reserves of the oil. 

6. It would become more and more difficult to extract oil in future. So petroleum is exhaustible.

B. Petroleum gas 

Petroleum can be extracted from under the sea bed. It can be extracted with giant drilling machines. The layer containing petroleum oil and gas is above that of water.

i) Coal : ExhaustIble :: Solar energy : InexhaustIble 

ii) Coaltar : Paints :: Coke : Manufacture of steel 

iii) Petrochemicals : Plastic :: CNG : Fertilizer 

iv) Carbondioxide: Global warming :: Heavy metals : Nausea

Coal, Petroleum and natural gas are examples of Exhaustible Natural Resources

The resources which are limited in nature and can be exhausted by human activities are called exhaustible resources, e.g. Coal, petroleum and natural gas.

(a) Fossil fuels are coal, petroleum and natural gas. 

(b) Process of separation of different constituents from petroleum is called refining. 

(c) Least polluting fuel for vehicles is CNG.

Due to the following reasons :

• Industrial effluents.
• Pesticides and insecticides.
• Chemical fertilizers.

D. bio gas 

Bio gas can be produced from raw materials such as agricultural waste, manure, plant material, green waste or food waste. It is a renewable source of energy. Natural gas, coal gas and petroleum gas are fossil fuels and are nonrenewable sources of energy.

Correct option is D) Both A and B

This is an open ended question. Let children imagine and write.

22 per cent.

Importance: Hydro power plants are of prime importance as about 25 per cent of our energy requirement in India is met by hydro Power Plants.

(i) A high rise dam is constructed at a suitable place on the river to obstruct the flow of water and thereby, collect water in larger reservoirs. Due to rise in water level the kinetic energy of flowing water is transformed into potential energy of stored water.
(ii) The water from the high level in the dam is carried through sluice gates and pipes to the turbine of electric generator, which is litted ar the bottom of the dam. Due to flowing water, turbine is rotated at a fast rate and hydel electricity is produced.
(iii) A hydro power plant converts the potential energy of falling/stored water into electricity.

Correct option  (C) Ocean Thermal Energy Conversion 

Explanation:

OTEC stands for Ocean Thermal Energy Conversion.

OTEC means Ocean Thermal Energy Conversion.

It is based on the temperature gradient between upper and lower layers of the ocean.

(i) Solar cells provide electricity in artificial satellites and space probes.

(ii) Used for street lighting, for traffic signals, for operating water pumps etc.

(iii) Used to operate electronic watches and calculators.

Tidal energy and Sea-wave energy.

Hint: Sunlight is present in unlimited quantity in nature whereas it takes millions of years to form petrol from dead remains of organisms.

These resources are present in unlimited quantity in nature and are not likely to be exhausted by human activities.

India is a country which is surrounded by water on three sides. This water is now used to generate electricity. Thus, hydropower plants are a good source of generating energy in India nowadays. 

Generation of electric energy in hydropower plant: - 

Electricity production in a hydropower plant works on the principle that- energy always remains conserve and one form of energy can be converted into other.

Water from a great height is poured on a turbine with very great speed. This is done to convert the potential energy of water into its kinetic energy. When this water falls on turbine, it moves with very high speed thus converting this kinetic energy of water into electric energy.

Koyna Hydroelectric Project is the largest hydroelectric power plant in Maharashtra

Correct option is C) Misusing energy sources

Correct option  (D) Statement 1 is false but statement 2 is true.

Explanation:

The box-type cooker can not be used where strong heating is required, tor example baking cake.

Burning of fossil fuels leads to the production of many acidic gases like sulphur-dioxide and nitrogen dioxides. These gases causes acid rain which damages trees, plants and buildings, reduces fertility of soil, and poses danger to aquatic life. The burning of fossil fuels puts a poisonous gas carbon monoxide in air. It also produces large amount of CO₂ gas which damages the environment in the long run by increasing the greenhouse effect. Also, burning of fossil fuels produces smoke and a lot of ash.

Pollution caused by the burning of fossil fuels can be controlled by the increasing the efficiency of combustion process and by using various techniques to reduce the escape of harmful gases and ash into the surrounding air.

Correct option is C) sunny day

The glass plate does not allow the heat to escape. This phenomenon is used in solar cookers as the solar cooker box is covered with a plane glass plate so as to capture more and more rays of the sun and allow maximum heating of the food placed in the box.

• Plane mirror reflect the sunlight thereby increasing the intensity of solar energy.
• Glass sheet prevents heat escape from solar cooker.

Solar cooker is covered with a glass sheet so as to trap the heat rays in the interior of the box of the cooker.

Advantages:
(i) The generation of electricity, from water does not produce any environmental pollution.
(ii) Water energy is a renenable source of electric energy which will never get exhausted.
Disadvantages:
(i) A vast variety of flora and fauna (plants and animals) get affected.
(ii) Dams can be constructed only at a limited number of places.

This is because when we are without clothes air carries away heat from our body due to convection and we feel cold

We know that earth absorbs heat in day and radiates at night. When sky is covered, with clouds, the heat radiated by earth is reflected back and earth becomes warmer. But if sky is clear the heat radiated by earth escapes into space.  

Limitations of wind energy: 

(i) Wind energy farms cannot be established everywhere. They can be established only at those places where wind blows for most part of the year. 

(ii) Wind energy farms require large area of land for their establishment.

(i) Deflection of compass needle increases. 

Magnetic field strength is directly proportional to the amount of current.

(ii) Deflection of the compass needle decreases.

Magnetic field strength is inversely proportional to the distance from the wire.

(a) Advantage of solar cell 

(i) They have no moving parts and require no maintenance.

(ii) They can be set up in remote and inaccessible areas 

(b) Disadvantage of solar cell 

(i) They are very expensive. 

(ii) They are less efficient. They can convert only about 25 % of light falling on them into electricity. 

(iii) They cannot work during night time.

When animals curl, they decrease their surface area and since energy radiated varies directly to surface area hence loss of heat due to radiation is also reduced.

a) Electrical energy produced by coal-fired plant = 2000MW = 2000x106W Electrical energy produced by wind turbine = 300kW = 300x103W No. of wind turbine required = 2000×106/300×103 = 6666.6 So, 6667 wind turbines would be needed to replace the power station. 

(b) In actual practice, this no. of wind turbines could not replace the coal-fired power plant because the efficiency of wind turbines keeps changing due to changes in wind speed but the efficiency of steam turbines used in coal-fired power stations remains the same. 

(a) Electrical energy produced by coal-fired plant = 2000MW = 2000x106W Electrical energy produced by wind turbine = 300kW = 300x103W No. of wind turbine required = 2000×106/300×103 = 6666.6 So, 6667 wind turbines would be needed to replace the power station.

(b) In actual practice, this no. of wind turbines could not replace the coal-fired power plant because the efficiency of wind turbines keeps changing due to changes in wind speed but the efficiency of steam turbines used in coal-fired power stations remains the same.

(b) a cloudy day.

(a) Breakdown of the power supply and break down of the setup arrangement. 

(b) Leakage of the radioactive materials and their harmful radiations 

(c) The nuclear energy if utilized with proper safety and conditions can certainly help us as a good source

The hazards of nuclear waste are: 

•The major hazard is Storage and disposal of spent or used fuel - as the uranium is still decaying into harmful subatomic particles. 

•Improper nuclear waste storage and disposal result in environmental contamination 

•There is a risk of accidental leakage.

(i) Aditya is taking a correct decision. It shows his awareness about energy conservation.

(ii) Solar heater runs on renewable source of energy. It saves electrical energy produced by burning fossil fuels, thus it helps in reducing global warming