Question

$\textbf{Choose the correct statements about the hydrides of group 15 elements.}$
A. The stability of the hydrides decreases in the order \(\text{NH}_3 > \text{PH}_3 > \text{AsH}_3 > \text{SbH}_3 > \text{BiH}_3\)
B. The reducing ability of the hydrides increases in the order \(\text{NH}_3 < \text{PH}_3 < \text{AsH}_3 < \text{SbH}_3 < \text{BiH}_3\)
C. Among the hydrides, \(\text{NH}_3\) is a strong reducing agent while \(\text{BiH}_3\) is a mild reducing agent.
D. The basicity of the hydrides increases in the order \(\text{NH}_3 < \text{PH}_3 < \text{AsH}_3 < \text{SbH}_3 < \text{BiH}_3\)
Choose the most appropriate from the option given below:

• A. A and B only
• B. C and D only
• C. B and C only
• D. A and D only

Answer 1

The Correct Option is C

Analysis of Statement A: The stability of hydrides does indeed decrease as we go down the group due to increasing atomic size and decreasing bond strength. Thus, the order is NH₃ > PH₃ > AsH₃ > SbH₃ > BiH₃ is correct.

Analysis of Statement B: The reducing ability of the hydrides increases down the group due to the increase in bond length and decrease in bond dissociation energy, making NH₃ < PH₃ < AsH₃ < SbH₃ < BiH₃ correct.

Analysis of Statement C: NH₃ does exhibit some reducing properties but is generally considered a weak reducing agent. On the other hand, BiH₃ can act as a mild reducing agent. Therefore, the statement is correct.

Analysis of Statement D: Basicity generally increases down the group, so NH₃ < PH₃ < AsH₃ < SbH₃ < BiH₃ is true.

Conclusion: Statements A and D are true, while statements B and C are indeed correct. Therefore, the best answer that reflects this is: B and C only