Chemistry

(i) Assertion and reason both are correct statements and reason is correct explanation for assertion.

Explanation: (i) In terms of 'Molarity (M), ' the number of moles of the solute dissolved per litre of solution is the strength of a solution.

(ii) Because the volume of a liquid changes with temperature, the volume of a solution changes as well, while the number of moles of solute in it remains constant (or unchanged). As a result, the molarity of the solution would be affected.

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(i)- (d);    (ii)- (c);    (iii)- (b);   (iv)- (e);    (v)- (a)

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(i)- (c);    (ii)- (e);    (iii)- (d);    (iv)- (a);    (v)- (b)

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(i)- (e);    (ii)- (c);    (iii)- (d);  (iv)- (b);    (v)- (a)

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(i)→ (e); (ii)→ (d); (iii)→ (a); (iv)→ (b) ; (v)→ (c)

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(i)→ (d); (ii)→ (e); (iii)→ (a); (iv)→ (c) ; (v)→ (b)

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(i)→ (c); (ii)→ (d); (iii)→ (b); (iv)→ (a)

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Options (i) and (ii) are correct since 75% of the solar energy reaching the earth is being absorbed by the earth's surface and this increases its temperature. The rest of the heat radiates back to the atmosphere. The average global temperature will increase to a level, and this leads to melting of polar ice caps and flooding of low-lying areas all over the earth. Increase in the global temperature increases the incidence of inectious diseases like malaria, dengue,   yellow fever etc.

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Options (ii), (iii) and (iv)  are correct since rainwater has a pH of 5.6 due to the presence of H+ ions formed by the reaction of rainwater with carbon dioxide present in the atmosphere. The reactions can be shown as-

H₂O (l)+CO₂ (g)→H₂CO₃ (aq)

H₂CO₃ (aq)→H+ (aq)+HCO₃ (aq)

If the pH of the rainwater falls below 5.6 then it is known as acid rain. SO₂ and NO₂ after oxidation and reaction with water are major contributors to the acid rain.

2SO₂ (g)+O₂ (g)+2H₂O (l)→2H₂SO₄ (aq)

4NO₂ (g)+O₂ (g)+2H₂O (l)→4HNO₃⁻ (aq)

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Options (i) and (ii) are correct since fertilizers contain phosphates as additives. The addition of phosphates in water enhances the growth of the algae. Such profuse growth of algae covers the water surface and reduces the oxygen concentration in water.