Assertion Reason Questions

For question given below, two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

(a) Both A and R are true and R is correct explanation of the assertion.
(b) Both A and R are true but R is not the correct explanation of the assertion.
(c) A is true but R is false.
(d) A is false but R is true.

Assertion: Different metals have different reactivities with water and dilute acids.
Reason: Reactivity of a metal depends on its position in the reactivity series.

Ans.1. (a)
The metals placed at the top of the series are most reactive.

Assertion: Iron is the most widely used metal. But it is never used in its pure state.
Reason: Pure iron is very soft and stretches easily when hot.

Ans.2. (a)

Assertion: Gold occurs in native state.
Reason: Gold is a reactive metal.

Ans.3. (c)
Gold is a noble metal.

Assertion: The property of beating a metal into sheets is called ductility.
Reason: Gold and silver are most malleable metals.

Ans.4. (d)
The property of beating a metal into sheets is called malleability.

Assertion: Silver and gold do not react with oxygen even at high temperatures.
Reason: Silver and gold are less active metals.

Ans.5. (a)

Assertion: The oxides of sulphur and phosphorus are acidic in nature.
Reason: Metal oxides are basic in nature.

Ans.6. (b)
Sulphur and phosphorus are non-metals. Non-metals form either acidic or neutral oxides.

Assertion: Bromine cannot displace chlorine from its salt solution.
Reason: Chlorine is more reactive than bromine.

Ans.7. (a)

Assertion: MgO exists in liquid state.
Reason: The electrostatic forces of attraction between Mg^{2+} and O^{2-} ions constitute ionic bond.

Ans.8. (d)
MgO exists in solid state.

Assertion: On reacting with water, calcium starts floating over water.
Reason: Calcium reacts with cold water at room temperature.

Ans.9. (b)
Calcium floats over water because the bubbles of hydrogen gas formed get stick to the surface of the water.

Assertion: The arrangement of metals in order of decreasing reactivities is called reactivity series.
Reason: Metals at the top of series are very reactive and metals at the bottom are least reactive.

Ans.10. (b)
Metals at the top of the series are very reactive and therefore, they do not occur free in nature. The metals at the bottom of the series are least reactive and therefore, they normally occur free in nature.

Assertion: Non-metals are electronegative in nature.
Reason: They have tendency to lose electrons.

Ans.11. (c)
Non-metals have a tendency to gain electrons.

Assertion: Ionic compounds have high melting and boiling points.
Reason: A large amount of energy is required to break the strong inter-ionic attraction in ionic compounds.

Ans.12. (a)

Assertion: Metals in general have very high melting and boiling points.
Reason: Metals have the strongest chemical bonds which are metallic in nature.

Ans.13. (a)

Assertion: Electrovalency of Na is +1.
Reason: The number of electrons which an atom either loses or gains in the formation of an ionic bond is known as its valency.

Ans.14. (a)

Assertion: Metals generally act as reducing agents.
Reason: The reducing character is expressed in terms of electron releasing tendency.

Ans.15. (b)
Metals have a strong tendency to lose electrons and hence they behave as reducing agents.

Assertion: Magnesium reacts with oxygen upon heating and burns brightly to form magnesium oxide.
Reason: Magnesium oxide is basic in nature.

Ans.16. (b)
Metals react with oxygen to form metal oxides which are basic in nature.

Assertion: The reaction of calcium with water is less violent in comparison to that of sodium.
Reason: The heat evolved is not sufficient for the hydrogen to catch fire.

Ans.17. (a)

Assertion: C and N do not react with dil. HCl and dil. H_{2}SO_{4} .
Reason: Metals do not react with dil. HCl and dil. H_{2}SO_{4} .

Ans.18. (c)
Metals react with dilute HCl and dil. H_{2}SO_{4} . Non-metals do not react with dilute acids.

Assertion: Copper displaces silver from silver nitrate solution.
Reason: Copper is more reactive than silver.

Ans.19. (a)

Assertion: Aluminum oxide and zinc oxide are acidic in nature.
Reason: Amphoteric nature means that substance have both acidic and basic character.

Ans.20. (d)
Aluminum and zinc oxides are amphoteric in nature.

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