Saccharin,an artificial sweetener,is manufactured from

Paraldehyde is used as a $ . . . . . . $.

What are the substances which mimic the natural chemical messengers?

In the given reaction scheme,$P$ is a phenyl alkyl ether,$Q$ is an aromatic compound; $R$ and $S$ are the major products.
$P$ $\xrightarrow{HI} Q$ $\xrightarrow[\text{(iii) } H_3O^{+}]{\text{(i) } CO_2, \text{(ii) } NaOH} R$ $\xrightarrow[\text{(ii) } H_3O^{+}]{\text{(i) } (CH_3CO)_2O} S$
The correct statement about $S$ is:

Which of the following drugs produce depression of the central nervous system?

$A$ medicine which promotes the secretion of urine is called: