RRB Group-D Model Paper 18 with answers for online practice

Explanation:

Fossil Fuels:

• Fossil fuels are formed by natural processes such as anaerobic decomposition of buried organisms under heat and pressure.
• Fossil fuels like coal, petroleum, natural gas contain high percentages of carbon.
• Fossil fuels are non-renewable resources and must be burned to release their energy.
• It releases sulphur, nitrogen, carbon, etc. gases in the atmosphere which causes the greenhouse effect and pollution.

The correct answer is Wood.

• Some exhaustible natural resources like coal, petroleum and natural gas,
• These were formed from the dead remains of living organisms (fossils).
• So, these are all known as fossil fuels.
• Coal is one of the fuels used to cook food.
• Earlier, it was used in railway engines to produce steam to run the engine.
• It is also used in thermal power plants to produce electricity. Coal is also used as fuel in various industries.
• 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.
• A natural fuel such as coal or gas, formed in the geological past from the remains of living organisms.

Unlike coal or crude oil, wood does not remain of a prehistoric organism, and therefore it is not fossil fuel - it's just fuel.