Consider the following chemical reaction.
$CH \equiv CH \xrightarrow[{(2) CO, HCl, AlCl_3}]{{(1) Red hot Fe tube, 873 K}} \text{Product}$
The number of $sp^{2}$ hybridized carbon atom$(s)$ present in the product is ..........

An ester $(A)$ with molecular formula $C_9H_{10}O_2$ was treated with excess of $CH_3MgBr$ and the complex so formed was treated with $H_2SO_4$ to give an olefin $(B)$. Ozonolysis of $(B)$ gave a ketone with molecular formula $C_8H_8O$ which shows positive iodoform test. The structure of $(A)$ is

The number of aldol reaction$(s)$ that occurs in the given transformation is :

Which of the following aldehydes will undergo the Cannizzaro reaction with a base?

Among the following,the marked proton of which compound shows the lowest $pK_{a}$ value?

Benzene carbaldehyde (benzaldehyde) is reacted with concentrated $NaOH$ solution to give the products $A$ and $B$. The product $A$ can be used as a food preservative and the product $B$ is an aromatic hydroxy compound where the $OH$ group is linked to an $sp^3$ hybridized carbon atom next to the benzene ring. The products $A$ and $B$ are respectively,