Lakhmir Singh Physics Class 10 Solutions Page No:132
Question 37: Fossil fuels are energy rich compounds of an element X which were originally made by the plants with the help of sun’s energy.
(a) Name the element X.
(b) Name another element which is usually found in combination with X in fossil fuels.
Solution : (a) X = Carbon
(b) Another element which is usually found in combination with carbon in fossil fuels is hydrogen.
Question 38: The energy in petrol originally came from the sun. Explain how it got into petrol.
Solution : Petrol is obtained from petroleum, which is a fossil fuel. Fossil fuels were originally made by sun’s energy because it was the sunlight of long ago that made plants and animals grow. So, the energy in petrol originally came from the sun.
Question 39: A substance X is added to LPG cylinders while filling so as to make the detection of leakage of LPG from the cylinders easy.
(a) Name the substance X.
(b) How does substance X make the detection of leakage of LPG easy ?
Solution : (a) X is ethyl mercaptan
(b) Ethyl mercaptan has a foul smell that can be detected easily.
Question 40: The pollution of air caused by burning petroleum fuels (like petrol and diesel) in vehicles can be controlled by fitting a device X in the exhaust system of vehicles.
(a) Name the device X.
(b) How does this device help in controlling air pollution ?
Solution : (a) Catalytic converter
(b) It converts poisonous carbon monoxide into non-poisonous carbon dioxide and harmful nitrogen oxides into harmless nitrogen gas.