Paper: CSIR-NET December 2018 · Subject: Inorganic Chemistry · Chapter: Acids and Bases · Topic: Acid and Bases – General · Marks: 2 · Difficulty: Medium
Consider compounds $\mathrm{PF_5}$, $\mathrm{SbF_5}$, $\mathrm{PH_3}$ and $\mathrm{SbH_3}$. The strongest acid and the strongest base among these are, respectively
(a)$\mathrm{PF_5}$ and $\mathrm{PH_3}$
(b)$\mathrm{SbF_5}$ and $\mathrm{PH_3}$
(c)$\mathrm{SbF_5}$ and $\mathrm{SbH_3}$
(d)$\mathrm{PF_5}$ and $\mathrm{SbH_3}$
Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
SbF₅ is the strongest fluoride acceptor (strongest Lewis acid); PH₃ is a stronger base than SbH₃ (lone pair less diffuse) — SbF₅ and PH₃ (b).