Which one of the following reactions will not result in the formation of a carbon-carbon bond?

An organic compound $X$ is oxidised by using acidified $K_2Cr_2O_7$ solution. The product obtained reacts with phenyl hydrazine but does not give the silver mirror test. The compound $X$ is,

Fehling's solution is a mixture of two solutions. One of them is $CuSO_4$. What does the other solution contain?

Benzaldehyde can be converted to benzyl alcohol in concentrated aqueous $NaOH$ solution using

The structure of product $C$,formed by the following sequence of reactions is :
$CH_3COOH + SOCl_2$ $\longrightarrow A$ $\xrightarrow[AlCl_3]{Benzene} B$ $\xrightarrow[H^{+}]{KCN} C$

Oxidation of ketones involves carbon-carbon bond cleavage. Name the products formed on the oxidation of $2,5-$dimethylhexan$-3-$one.