What is the minimum number of carbon atoms required for an alkane to contain a quaternary carbon atom?

$RMgI$ when treated with ice-cold water liberated a gas which occupied $1.4 \text{ dm}^3/\text{g}$ at $STP$. The gas produced is further reacted with iodine in the presence of $HIO_3$ to give compound $(X)$. Compound $(X)$ in the presence of $Na$ and dry ether produced compound $(Y)$. The molar mass of compound $(Y)$ is . . . . . . $\text{g mol}^{-1}$. (Nearest integer)

In the following reaction $C$ is,$CH_3-CH=CH_2 + HCl$ $\xrightarrow[\text{Peroxide}]{\text{Organic}} A$ $\xrightarrow[\text{Moist}]{\text{Ag}_2\text{O}} B$ $\xrightarrow{\text{EtMgBr}} C$

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

Which compound produces methane gas upon reaction with water?

Which gas is liberated when $Al_4C_3$ is hydrolysed?