Question

31 Assertion: Hydrogen gas is not evolved when a metal reacts with nitric acid.

Reason: Nitric acid is a strong oxidising agent and it oxidises the H2 produced to water and itself gets reduced to oxides of nitrogen.

32 Assertion: Sky appears blue in colour.

Reason: When sunlight enters the atmosphere of earth, it undergoes refraction.

33 Assertion: Ionic compounds have high melting and boiling points.

Reason: A considerable amount of energy is required to break the strong inter- ionic attraction.

34 Assertion: Blood circulation in human beings is double circulation.

Reason: Purification of blood takes place twice in left and right chambers of heart.

35 Assertion: Sodium bicarbonate is used as antacid.

Reason: Sodium bicarbonate is acidic in nature.​

Answer 1

Chemistry is the study of substances—that is, elements and compounds—while biology is the study of living things. ... Thus chemistry involves the study of the atomic composition and structural architecture of substances, as well as the varied interactions among substances that can lead to sudden, often violent reactions.