Question

Assertion: Thallium (III) hydroxide is highly soluble in water.
Reason: Thallium (III) hydroxide is the most basic among 13th group hydroxides.

• A. Assertion is True, Reason is True, Reason is a correct explanation of Assertion
• B. Assertion is True, Reason is True, Reason is not a correct explanation of Assertion
• C. Assertion is True, Reason is False
• D. Assertion is False, Reason is True

Answer 1

The correct option is D Assertion is False, Reason is True

$T{l}^{+3}$ ion has very high lattice energy and very low solubility product $(K_{sp}=6.3\times {10}^{46})$. Among group 13 hydroxides, thallium (III) hydroxide has lowest solubility. Hence the statement 1 is false. On moving down the group 13, the hydroxides change their character from acidic to amphoteric to basic.
$Tl(OH{)}_3$ is the most basic among group 13 hydroxides. Hence the statement 2 is true.