Question

Assertion :Stannous chloride gives grey precipitate with mercuric chloride, but stannic chloride does not do so. Reason: Stannous chloride is a powerful oxidising agent which oxidises mercuric chloride to metallic mercury.

• A. If both assertion and reason are true and the reason is a correct explanation of the assertion
• B. If both assertion and reason are true but reason is not a correct explanation of the assertion
• C. If the assertion is true but reason is false
• D. If both the assertion and reason are false

Answer 1

The correct option is C If the assertion is true but reason is false

$S{n}^{4+}$ is more stable than $S{n}^{2+}$. So, $S{n}^{2+}$ is oxidised to $S{n}^{4+}$ by losing 2 electrons when it reacts with mercuric chloride, i.e., $SnC{l}_2$ is a reducing agent.
$2HgC{l}_2+SnC{l}_2⟶H{g}_{2}C{l}_2+SnC{l}_4$
$H{g}_{2}C{l}_2+SnC{l}_2⟶2Hg+SnC{l}_4$
(grey ppt)
So assertion is correct but reason is wrong. Hence correct option is (C).