In the reaction $CH_3CHO + HCN \to CH_3CH(OH)CN$,a chiral centre is produced. This product would be

The major product $Q$ of the following reaction scheme is:

Identify the products $A$,$B$,and $C$ in the following reaction sequence:
$C_6H_5CONH_2$ $\xrightarrow{P_2O_5, \Delta} A$ $\xrightarrow[(ii) H_2O]{(i) DIBAL-H} B$
$A \xrightarrow[(ii) H_3O^+, \Delta]{(i) (CH_3CO)_2O/CH_3COONa} C$

The major product $'P'$ formed in this reaction is:

Assertion : Aldol condensation can be catalysed both by acids and bases.
Reason : $\beta$-Hydroxyaldehydes or ketones readily undergo acid-catalysed dehydration.

The reaction of butanal with $n$-propylmagnesium bromide gives a