Question

Assertion (A): Ammonia has hydrogen bonding whereas $\mathrm{HCl}$ has no hydrogen bonding.

Reason (R): Nitrogen has greater electronegativity than chlorine.

• A. Both A and R are true and R is the correct explanation of A.
• B. Both A and R are true, but R is not the correct explanation of A.
• C. A is true and R is false.
• D. A is false and R is true.

Answer 1

The correct option is C

A is true and R is false.

Explanation of the correct option:

Assertion:

• Ammonia shows hydrogen bonding.
• The structure is ${\mathrm{H}}_3\mathrm{N}\cdots \cdots \mathrm{H}-{\mathrm{NH}}_2$.
• In the case of $\mathrm{HCl}$, despite its electronegativity, the size of a chlorine ($\mathrm{Cl}$) atom is larger and hence, the electron density is low.
• So, $\mathrm{HCl}$ does not have hydrogen bonding.

So, the statement for the assertion is correct.

Reason:

• Chlorine is more electronegative than nitrogen.
• Electronegativity is the tendency of an element to attract the bond pair electron towards itself.
• From left to right of the periodic table the electronegativity increases, due to an increase in effective nuclear charge.
• Though chlorine belongs to the third period, it has $17$protons due to which its size shrinks and electronegativity increases.

Thus, the statement given for reason is wrong.

Therefore, A is true and R is false.

Hence, the correct option is (C).