Question

Assertion: $S{F}_6$ cannot be hydrolysed but $S{F}_4$ can be.
Reason: Six F atoms in $S{F}_6$ prevent the attack of $H_{2}O$ on sulphur atom of $S{F}_6$.

• A. Both assertion and reason are correct statements, and reason is the correct explanation of the assertion
• B. Both assertion and reason are wrong statements.
• C. Assertion is wrong but reason is correct statement
• D. Both assertion and reason are correct statements, but reason is not the correct explanation of the assertion.
• E. Assertion is correct but reason is wrong statement.

Answer 1

The correct option is A Both assertion and reason are correct statements, and reason is the correct explanation of the assertion

Analysing the assertion



$S{F}_6$ has octahedral geometry and attack of water molecule is not easy due to steric crowding where the sulphur atom is surrounded by 6 fluorine atoms.
$S{F}_4$ has see-saw shape and there is enough space for the coming nucleophile.

So, the assertion is correct.

Analysing the Reason

Fluorine atoms are highly electronegative, they attract electron clouds towards them in $S{F}_6$ due to which fluorine atoms come even closer, and a compact octahedral structure is formed.

Due to this compact structure, the $H_{2}O$ molecule is incapable of donating electrons to S and thus no attack of $H_{2}O$ on the sulphur atom takes place.

But due to see-saw structure and empty d- orbitals of S, $S{F}_4$ can be hydrolysed by water.
So, the reason is also correct.

Thus, assertion and reason both are correct, and reason is the correct explanation of assertion.

Hence, option (A) is correct.