Question

Assertion :Aluminium forms $[Al{F}_6{]}^{3-}$ but B does not form $[B{F}_6{]}^{3-}$ Reason: $B{F}_3$ on hydrolysis gives $HB{F}_4$

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is C Assertion is correct but Reason is incorrect

Aluminium forms $[Al{F}_6{]}^{3-}$ but B does not form $[B{F}_6{]}^{3-}$ due to the large size of Al and availability of d-orbitals for Al. B is small sized and has no vacant d orbitals.
$B{F}_3$ does not undergoes hydrolysis due to strong B-F bond. It gives an addition product.

$B{F}_3+2H_{2}O\to H_3{O}^{+}[B{F}_{3}OH{]}^{-}$
Hence, the assertion is correct but the reason is incorrect.