Page 54 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

Plants, soil, buildings and animals are affected by acid rain. Three adverse effects of

acid rain are :
• It weakens the trees or plants, the acid deposits rob the soil of essential

nutrients, such as calcium and cause aluminum to be released in the soil, which
makes it hard for trees to take up water.

• Acid rain increases the acidic content in soil and waterbodies thus making
it unsuitable for animals and plants to survive. It deteriorates the texture of

buildings made of marble and limestone, such as monuments etc.
• Structures made of steel also get corroded due to acid rain.

4. Name three mineral acids and write their formulae.
Ans. Three mineral acids are as follows :

(a) Hydrochloric acid : It is a strong acid that is commonly used in laboratory and
industrial applications. It is a solution of hydrogen and chlorine gas in water. It

is naturally found in the stomach of humans, where it helps in the digestion of
food.

Its chemical formula is HCl.
(b) Sulphuric acid : It is a highly corrosive, dense and oily liquid. It is widely used in

the manufacture of fertilizers, explosives and in the refining of petroleum.
Its chemical formula is H SO .
2 4
(c) Nitric acid : It is a higly corrosive & toxic acid used in the production of fertilizers,
explosives and in the chemical industry.

Its chemical formula is HNO .
3
5. Classify the following as acids and bases and give a reason for each.

Tomato juice, tamarind juice, curd, toothpaste, soap solution, raw mangoes.
Ans. (a) Tomato Juice : It is an acid. It contains citric acid and ascorbic acid, that give it a

sour taste, indicating its acidic nature.
(b) Tamarind Juice : It is an acid. It is rich in tartaric acid, which gives it a tangy

taste, which is a chartacteristic of acidic substances.
(c) Curd : It is an acid. It contains lactic acid, which gives it a slightly sour taste.

(d) Toothpaste : It is a base. It generally contains substances like sodium bicarbonate
or calcium carbonate, which are basic in nature and help neutralize acids in the

mouth to prevent tooth decay.
(e) Soap solution : It is a base due to the presence of compounds like sodium

hydroxide or potassium hydroxide used in the their manufacture.
(f) Raw Mangoes : It contains citric acid giving it a sour taste, indicating their acidic

nature.

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