Q21 of 23 Page 63

Hritik tested rainwater and found a pH of 5-6 due to presence of H+ ions formed by reaction of rainwater with carbon dioxide. When pH of the rainwater drops below 5-6, then it is called acid rain. Oxides of nitrogen and sulphur are acidic in nature. Burning of fossil fuels such as coal and oil in power stations and furnace produce oxides of nitrogen and sulphur. He told all of his classmates living nearby to use bicycle instead of school bus so as to reduce air pollution and prevent acid rain.

(a) Which acid is formed by sulphur dioxide in presence of air?


(b) Which acid is formed by nitrogen dioxide in presence of air?


(c) Why is acid rain harmful for agriculture, trees and plants?


(d) How can we prevent from acid rain?


(e) What values are possessed by Hiritik?

a. Sulfuric acid, sulphurous acids are formed by sulphur dioxide in presence of air.

b. Nitric acid is formed by nitrogen dioxide in presence of air.


c. Plants, agricultural crops and trees require an optimum pH for their survival. Due to acid rain, the pH balance of the soil is disturbed and the soil becomes more acidic. This acidic nature of the soil is very much harmful to the healthy growth of plants, agricultural crops and trees. In this way, acid rain is harmful to agriculture, trees and plants.


d. We can prevent acid rain by controlling pollution, by controlling the rate of consumption and burning of fossil fuels such as coal and petroleum oil, by controlling automobile combustion, reducing the burning of wastes, filtering out particulate matters emitted from the industries, using cleaner fuels like CNG in the automobiles and start using renewable sources of energy like solar energy, wind energy, tidal energy etc for electricity generation.


e. Hritik possesses the value of social responsibility. He is very much concerned for his environment and the health of the society as a whole.


More from this chapter

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17

In the following schematic diagram for the preparation of hydrogen gas as shown in the given figure, what would happen if the following changes are made?


(a) In place of zinc granules, same amount of zinc dust is taken in the test tube.


(b) Instead of dilute sulphuric acid, dilute hydrochloric acid is taken.


(c) In place of zinc, copper turnings are taken.


(d) Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated.

18

(a) Identify the acid and the base whose combination forms the common salt that you use in your food. Write its formula and chemical name of this slat. Name the source from where it is obtained.

(b) What is rock salt? Mention its colour and the reason due to which it has this colour.


(c) What happens when electricity is passed through brine? Write the chemical equation for it.

19

(a) Identify the compound of calcium which is yellowish white powder and is used for disinfecting drinking water. Write its chemical name and formula. How is it manufactured? Write the chemical equation for the reaction involved. Also list two other uses of the compound.

(b) Write the balanced chemical equation of chlor-alkali process.

20

(a) Crystals of a substance changed their colour on heating in a closed test tube but regained it after sometime when they were allowed to cool down. Name the substance and write its formula and explain the phenomenon involved.

(b) Name the compound whose one formula unit is associated with 10 water molecules. How is it prepared? Give equations of related reactions. Give two uses of the compound.