ABC26IN0197 · Main Group Elements

Subject: Inorganic Chemistry · Chapter: Main Group Elements · Topic: Hydrides · Exam: CSIR-NET 2015 · Marks: 2 · Difficulty: Hard

The order of increasing Bronsted acidity for boron hydrides is
(a)$\mathrm{B}_{5} \mathrm{H}_{9}<\mathrm{B}_{6} \mathrm{H}_{10}<\mathrm{B}_{10} \mathrm{H}_{14}$
(b)$\mathrm{B}_{10} \mathrm{H}_{14}<\mathrm{B}_{5} \mathrm{H}_{9}<\mathrm{B}_{6} \mathrm{H}_{10}$
(c)$\mathrm{B}_{6} \mathrm{H}_{10}<\mathrm{B}_{10} \mathrm{H}_{14}<\mathrm{B}_{5} \mathrm{H}_{9}$
(d)$\mathrm{B}_{10} \mathrm{H}_{14}<\mathrm{B}_{6} \mathrm{H}_{10}<\mathrm{B}_{5} \mathrm{H}_{9}$
Answer
Answer (as printed): A
Explanation
Acidic strength of boranes depends upon (i) number of boron atoms (ii) decapping. Hence, the correct order of acidity is $\mathrm{B_5H_9} < \mathrm{B_6H_{10}} < \mathrm{B_{10}H_{14}}$.

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