JEE Chemistry 2026 Question with Solution

Given: Hydrides of group $15$ elements are $EH_3$ where $E = N, P, As, Sb$.

Find: Which of statements A, B, C, D are correct.

Concept: Down group $15$, atomic size increases and the $E-H$ bond strength decreases. This affects stability, basicity, reducing character, and boiling point.

Step 1: Stability of hydrides

Due to decreasing $E-H$ bond strength down the group, the stability decreases down the group. Therefore, statement A is true.

Step 2: Basicity of hydrides Basicity depends on availability of the lone pair. As size increases, the lone pair becomes less available.

So, the basicity decreases down the group. Therefore, statement B is true.

Step 3: Reducing character Reducing character increases as the $E-H$ bond weakens down the group.

Therefore, statement C is true.

Step 4: Boiling point Although $\text{NH}_3$ shows hydrogen bonding anomaly, the overall boiling point increases down the group due to increasing molar mass. Therefore, statement D is true.

Conclude: All four statements are correct. The correct option is A.

Given: The hydrides are $\text{NH}_3, \text{PH}_3, \text{AsH}_3, \text{SbH}_3$.

Find: Use periodic trends to test each statement.

1. Stability depends strongly on bond strength. Since the size of the central atom increases down the group, overlap with $1s$ of hydrogen becomes poorer and the $E-H$ bond becomes weaker. Hence stability decreases.
2. Basicity decreases down the group because the lone pair is held in a larger, more diffuse orbital and is less available for donation.
3. Reducing character increases because weaker $E-H$ bonds are broken more easily.
4. Boiling point generally increases down the group because intermolecular forces increase with molar mass, even though $\text{NH}_3$ shows hydrogen bonding.

Therefore, A, B, C and D are all correct, so the correct option is A.