NCERT Solutions Class 8 Science Chapter 5 Coal and Petroleum

Question :1. What are the advantages of using CNG and LPG as fuels?

Answer :
The advantage of using CNG and LPG are as follows:

a. These are cleaner fuels.

b. These are low cost fuels.

c. These are available easily.

d. These can be supplied through pipes.

Question :2. Name the petroleum product used for surfacing of roads.

Answer :
These days bitumen, a petroleum product is used for surfacing the roads in place of coal tar.

Question :3. Describe how coal is formed from dead vegetation. What is this process called?

Answer :
Million years ago, earth was having dense forests in low lying wet land areas. Due to earthquakes and volcanic eruptions, these forests got buried under the soil. As more soil deposited over them, they were compressed. The temperature also raised as they sank deeper and deeper. Due to high temperature and lack of oxygen dead plants inside the earth got slowly converted to coal. This process of coal formation is called carbonization.

Question :4. Fill in the blanks.

(a) Fossil fuels are ________, ______________, and ________________.

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

(c) Least polluting fuel for vehicle is ________________.

Answer :
(a) Coal, Petroleum and Natural gas.

(b) Refining

(c) CNG

Question :5. Tick true/False against the following statements.

(a) Fossils fuels can be made in laboratory. (T/F)

(b) CNG is more polluting fuel than petrol. (T/F)

(c) Coke is almost pure form of carbon. (T/F)

(d) Coal tar is a mixture of various substances. (T/F)

(e) Kerosene is not a fossil fuel. (T/F)

Answer :
Tick True/false.

(a) FALSE (b) FALSE (c) TRUE (d) TRUE (e) FALSE

Question :6. Explain why fossil fuels are exhaustible natural resources.

Answer :
Fossils fuels are present in nature in limited quantity and are being exhausted abundantly by us. That is why fossil fuels are called exhaustible natural resources.

Question :7. Describe characteristics and uses of coke.

Answer :
Coke is a tough porous black substance. It is almost pure form of carbon. It is used in the manufacture of steel and in the extraction of many metals.

Question :8. Explain the process of formation of petroleum.

Answer :
Petroleum is formed from organism living in the sea. When these organism died, their bodies settled at the bottom of the sea and got covered with layers of the sand and clay. Over millions of years, they were transformed into petroleum oil and natural gas under the absence of air and presence of high temperature and high pressure.