Ozonolysis of an organic compound gives formaldehyde as one of the products. This indicates the presence of:

The product $(C)$ is:

$Propanal$ and $pentan-3-one$ are ozonolysis products of:

The major product formed in the following reaction is:

$A$ hydrocarbon with molecular formula $C_6H_{10}$ absorbs only one molecule of $H_2$ upon hydrogenation. Ozonolysis of the hydrocarbon yields $OHC-CH_2-CH_2-CH_2-CH_2-CHO$. The hydrocarbon is:

Following are the four molecules $P$,$Q$,$R$ and $S$. Which one among the four molecules will react with $HBr_{(aq)}$ at the fastest rate?