Which of the following compounds undergoes the Cannizzaro reaction?

Predict the product in the given reaction:
$3-\text{chlorobenzaldehyde} \xrightarrow{50\% \text{KOH}, \Delta} ?$

Acetaldehyde reacts with $C_2H_5MgCl$. The final product is

Predict the products formed when cyclohexanecarbaldehyde reacts with the following reagents:
$(i)$ $PhMgBr$ and then $H_3O^{+}$
$(ii)$ Tollens' reagent
$(iii)$ Semicarbazide and weak acid
$(iv)$ Excess ethanol and acid
$(v)$ Zinc amalgam and dilute hydrochloric acid

An organic compound with the molecular formula $C_9H_{10}O$ forms a $2,4-DNP$ derivative,reduces Tollen's reagent and undergoes Cannizzaro reaction; on vigorous oxidation it gives $1,2-$benzenedicarboxylic acid. The structure of the organic compound is:

For the given compound,determine the number of hydrogen atoms that are replaced by $D$ upon keeping it for a long time with $\mathop O\limits^\ominus D / D_2O$.