The relation between $K_1$ and $K_2$ for the given equilibrium reactions is:

Given below are two statements:
Statement $I$: Cross aldol condensation between two different aldehydes will always produce four different products.
Statement $II$: When semicarbazide reacts with a mixture of benzaldehyde and acetophenone under optimum pH, it forms a condensation product with acetophenone only.
In the light of the above statements, choose the correct answer from the options given below:

$R-C(=O)H + R-NH_2 \rightarrow R-CH=N-R$. This reaction gives the best yield at:

The structures of major products $A$, $B$, and $C$ in the following reaction sequence are:

Acetaldehyde can be converted into $C(CH_2OH)_4$ (pentaerythritol) by which reagent?

Find out the major product from the following reaction: