What is the number of $-CH_2-$ groups present in dodecane?

$A$ hydrocarbon $C_{5}H_{10}$ does not react with chlorine in the dark but gives a single monochloro compound $C_{5}H_{9}Cl$ in bright sunlight. Identify the hydrocarbon.

$LPG$ mainly consists of the following:

The provided image shows a chemical reaction: $R' - X \xrightarrow{Na / \text{ether}} ?$. This is the Wurtz reaction. Identify the product formed in this reaction.

In the preparation of alkanes,a concentrated aqueous solution of sodium or potassium salts of saturated carboxylic acids is subjected to:

What is the use of $tetraethyl$ lead $(TEL)$?