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ScienceClass 8CBSE

1. The underlined words in the following sentences have been jumbled up. Write them in their correct form. (a) Loca is obtained from mines. (b) Umpetlore is a fossil fuel. (c) Rineryfe is a place where various fractions of peroleum are separated. (d) Keenrose is a fuel used in jet crafts. (e) Nutsgilh is an example of inexhaustible natural resources.

coal petroleum refinery kerosene sunlight

ScienceClass 8CBSE

Fill in the blanks in the following sentences. (a) Coal is one of the used to cook food. (b) When heated in air, coal burns and produces mainly gas. (c) Coal tar is a black, thick with an smell. (d) Petroleum, and are fossil fuels. (e) Forests and coal are natural resources.

Coal is one of the fuel used to cook When heated in air, coal burns and produces mainly Carbon-di-oxide Coal tar is a black, thick liquid with an unpleasant Petroleum, Coal and natural gas are fossil Forests and coal are exhaustible natural

ScienceClass 8CBSE

Name the petroleum product used as fuel for stoves, lamps and jet aircrafts.

Kerosene is the petroleum product used as fuel for stoves, lamps and jet aircrafts.

ScienceClass 8CBSE

What does CNG stand for and why is it considered to be a better fuel than petrol?

CNG stands for compressed natural gas. CNG burns with no smoke hence it does not cause air pollution. CNG does not produce any poisonous gas hence CNG is considered a better fuel than petrol.

ScienceClass 8CBSE

You are provided with a mixture of petroleum and water. Can you suggest a method to separate the two?

Decantation method is used to separate mixture of petroleum and water.

ScienceClass 8CBSE

Choose the incorrect statement from the following: (a) It is difficult to transport natural gas through pipes. (b) The disadvantage of natural gas is that it can not be used directly for burning in homes. (c) Natural gas is stored under high pressure as compressed natural gas. (d) Natural gas cannot be used for power generation.

Soln: Answer is (d) Natural gas cannot be used for power generation. Explanation: Natural gas can be used for power generation hence statement d) is wrong

ScienceClass 8CBSE

Petroleum was formed from organisms: (a) living on the land (b) living on the plants (c) living in the sea living on the rocks

Soln: Answer is (c) living in the sea Explanation: Petroleum was formed from organisms living in the sea. As these organisms died, their bodies settled at the bottom of the sea and got covered with layers of sand and clay. Over millions of years, absence of air, high temperature and high pressure transformed the dead organisms into petroleum and natural gas.

ScienceClass 8CBSE

Which of the following is not a constituent of petroleum? (a) paraffin wax (b) lubricating oil (c) petrol coke

Soln: Answer is (b) lubricating oil Explanation: Lubricating oil is obtained from crude petroleum.

ScienceClass 8CBSE

Naphthalene balls are obtained from coal tar and are used as (a) mosquito repellant (b) honey bee repellant (c) moth repellant snake repellant

Answer is (c) moth repellant Explanation: Characteristic smell of naphthalene makes the insects and moth run away from naphthalene stored under clothes etc.

ScienceClass 8CBSE

Coal is formed from the remains of (a) vegetation only (b) animals only (c) both vegetation and animals neither vegetation nor animals

Answer is (d) neither vegetation nor animals Explanation: Coal is formed 300 million years ago when buried plants and trees get decomposed.

ScienceClass 8CBSE

Which substance is formed by the carbonisation of dead vegetation?. (a) coal (b) coke (c) coal gas coal tar

Ansswer is (a) coal Explanation: Coal is formed 300 million years ago when buried plants and trees get decomposed.

ScienceClass 8CBSE

1. Fossil fuels are obtained from: (a) remains of non-living materials. (b) dead remains of birds only. (c) dead remains of insects only. (d) dead remains of living organisms.

Answer is (a) remains of non-living materials. Explanation: Fossil fuels are obtained millions of years ago remains of non-living materials. Get buried under the earth.

ScienceClass 8CBSE

Exhaustible natural resources are: (a) unlimited in quantity. (b) not dependent on nature. (c) limited in quantity. (d) not exhausted by human activities.

Answer is (c) limited in quantity. Explanation: Exhaustible natural resources are limited and they get exhausted by human activities.

ScienceClass 8CBSE

1. Coal is processed in industries to get some useful products. Which of the following is not obtained from coal? (a) coke (b) coal tar (c) coal gas (d) CNG

Soln: Answer is (d) CNG Explanation: CNG is compressed natural gas which is made by compressing the natural gas. CNG is a petroleum product whereas other options provided are obtained from coal.

ScienceClass 8CBSE

Which of the following is a pair of exhaustible natural resources. (a) coal and soil (b) air and sun-light (c) water and petroleum wild life and minerals

Soln: Answer is (d) wild life and minerals Explanation: In option a there is soil, In option b there is sunlight and in option c there is water which will not get exhausted hence option d) is right.

ScienceClass 8CBSE

Air is a natural resource and cannot be exhausted by human activities. It is known as inexhaustible natural resource. Which of the following is another inexhaustible natural resource? (a) coal (b) petroleum (c) sun-light minerals

Soln: Answer is (c) sun-light Explanation: Petroleum and minerals are non-renewable sources of energy which can get exhausted whereas sunlight is a renewable resource.

ScienceClass 8CBSE

Various materials which are obtained from nature are called natural resources. Which of the following is not a natural resource? (a) minerals (b) water (c) soil plastic

Answer is (d) plastic Explanation: Minerals, water and soil are natural resources whereas plastic is a man made substance.

ScienceClass 8CBSE

Despite being very useful it is advised to restrict the use of plastic. Why is it so? Can you suggest some methods to limit its consumption?

Plastic is a non-biodegradable material which poses serious threat to the nature. Disposing of plastic waste is the biggest problem we face to regret the use of plastics. Plastics cause soil pollution and air pollution on burning. Usage of plastic should be reduced and used plastic should be recycled and reused to reduce its consumption.

ScienceClass 8CBSE

Write the importance of synthetic polymers in our life.

Following are the points to justify the importance of synthetic polymers in our life. Nylon It is used for making ropes for rock climbing, fishing nets, raincoats, parachutes and tyre cords, Acrylic It is used for sweaters, tracksuits, linings for boots and gloves and In furnishing fabrics and Terylene It is used in the textile industry to make clothes like sarees, tapestry and dress It is also mixed with a natural fibre like cotton and wool to make more variety of clothes. Plastics It is used to store food item, water, milk, pickles, dry food, etc. Plastic containers seem most convenient. This is because of lightweight, low price, good strength and easy handling as compared to Plastics are used in cars, air crafts and spacecraft.

ScienceClass 8CBSE

Indicate whether the following statements are True or False. Also write the false statements in their correct form. (i) The fabric terywool is obtained by mixing terylene and wool. (ii) Synthetic fibres do not melt on heating. (iii) It is risky to wear synthetic clothes while working in the kitchen. (iv) Most of the plastics are biodegradable.

True False- Synthetic fibres do not melt on True because synthetic clotes melts on exposure to heat False- Plastics are non-biodegradable

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