Question

Assertion: ${\mathrm{HNO}}_3$ is a stronger acid than ${\mathrm{HNO}}_2$.

Reason: In ${\mathrm{HNO}}_3$ there is two nitrogen to oxygen bonds whereas in ${\mathrm{HNO}}_2$ there is only one.

• A. Both Assertion and Reason are false.
• B. Assertion is true, but Reason is false.
• C. Both Assertion and Reason are true. The reason is the correct explanation of Assertion.
• D. Both Assertion and Reason are true. The reason is not the correct explanation of Assertion.

Answer 1

The correct option is B

Assertion is true, but Reason is false.

Explanation for assertion statement

Conjugate acid

• When a proton is added to a base, a conjugate acid is formed.
• Conjugate acids have one extra proton compared to the species that is forming it.

Conjugate base

• When a proton is removed from an acid, a conjugate base is formed.
• Conjugate bases have one proton less and one more negative charge compared to the species that is forming it.

Stronger acid

• ${\mathrm{HNO}}_3$ is a stronger acid than ${\mathrm{HNO}}_2$, for the following reasons.
• ${\mathrm{HNO}}_3\text{'}\mathrm{s}$ conjugate base $\left({\mathrm{NO}}_3^{-}\right)$is more stable than ${\mathrm{HNO}}_2\text{'}\mathrm{s}$ conjugate base$\left({\mathrm{NO}}_2^{-}\right)$.
• Because in case of $\left({\mathrm{NO}}_3^{-}\right)$, the charge is dispersed on three oxygen atoms, and in case of $\left({\mathrm{NO}}_2^{-}\right)$, the charge is dispersed on two oxygen atoms.

Explanation for reason statement

• The structure of ${\mathrm{HNO}}_3$ is as follows:-
• 
• The structure of ${\mathrm{HNO}}_2$ is as follows:-
• 
• Hence, in ${\mathrm{HNO}}_3$ there are three oxygen is attached to nitrogen whereas in ${\mathrm{HNO}}_2$, two oxygen is attached to the nitrogen.
• Hence, the given reason in the question is incorrect.

Hence, option(B) is the correct answer.