The p-Block Elements (XII)

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Q1.

Assertion (A):	Nitrogen and Oxygen are the main components in the atmosphere but these do not react to form oxides of nitrogen.
Reason (R):	The reaction between nitrogen and oxygen requires a high temperature.

Both(A)and(R)are True and(R)is the correct explanation of(A).
Both(A)and(R)are True but(R)is not the correct explanation of(A).
(A)is True but(R)is False.
Both(A)and(R)are False.

Explanation:

Hint: The reaction of nitrogen and oxygen depends upon the temperature.
Both $N_{2} and O_{2}$ are less reactive at ordinary conditions. The reaction between nitrogen and oxygen requires a high temperature. N₂ bond order is 3 and it is non reactive at room temperature. Thus, it will not reacts with O₂

The bond dissociation energy of N₂ and O₂ is as follows:

N₂ = 945 kJ/mol
O₂ = 498 kJ/mol

Hence, both assertion and reason are correct, and the reason is the correct explanation for the assertion.

Q2. The incorrect statement regarding ammonia is:

Ammonia is a colorless gas with a pungent odor.
Ammonia is used for the manufacture of nitric acid.
As a weak base, it precipitates the hydroxides of many metals from their salt solutions.
Ammonia molecule is trigonal planar with the nitrogen atom at the apex.