Which of the following has the highest knocking property?

Alkanes are generally resistant to oxidation under mild conditions. What is your opinion regarding the following reaction?
$C_4H_{10(g)} + \frac{13}{2}O_{2(g)} \to 4CO_{2(g)} + 5H_2O_{(l)}$

In the preparation of $n$-butane by the reaction of $C_2H_5I$ with $Na$ in the presence of ether,which of the following impurities is involved?

$A$ saturated hydrocarbon possesses $2$ carbon atoms and all its hydrogen atoms are of the same type. Provide the structure and the type of hydrogen atoms present.

$A$ hydrocarbon of molecular mass $72 \ g \ mol^{-1}$ gives a single monochloro derivative and two dichloro derivatives on photochlorination. Give the structure of the hydrocarbon.

Electrolysis of potassium acetate yields .........