The major product of the reaction is:

In the given reaction,what will be the structure of $Z$?

How can ethene be produced from ethanol?

The reaction is given as:
$(CH_3)_2C=C(CH_3)_2 + (CH_3)_3N^{+}-O^{-} + H_2O \xrightarrow{OsO_4 (10^{-4} \text{ mole})} A + (CH_3)_3N$
Product $(A)$ is:

The metal used for the de-bromination reaction of $1, 2$-dibromoethane 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?