$A$ hydrocarbon contains $86\%$ carbon. $488 \ mL$ of the hydrocarbon weighs $1.68 \ g$ at $STP$. Then the hydrocarbon is an:

The compounds that will give an isomer of $2,2$-dimethylpropane on catalytic hydrogenation are:
$(1)$ $CH_3-CH=C(CH_3)_2$
$(2)$ $CH_3-CH=CH-CH_3$
$(3)$ $CH_3-CH=CH-CH_2-CH_3$
$(4)$ $CH_3-C(CH_3)=C(CH_3)-CH_3$

The product $(A)$ formed in the following reaction sequence is :
$CH_3-C \equiv CH$ $\rightarrow[(ii) HCN]{(i) Hg^{2+}, H_2SO_4}$ $\xrightarrow[(iii) H_2 / Ni]{} (A)$

An unknown alkene $(A)$ reacts with $3 \ mole$ of $H_2$ gas in the presence of a platinum catalyst to form $1$-isopropyl-$4$-methylcyclohexane. When the unknown alkene $(A)$ is ozonized and reduced,the following products are obtained:
$HCHO$,$OHC-CH_2-CO-CO-CH_3$,and $CH_3-CO-CH_2-CHO$
What is the structure of alkene $(A)$?

Which of the following alkenes will give $CH_3CH_2CHO$ and $CH_3COCH_3$ upon ozonolysis?

Which of the following is most reactive for electrophilic addition reaction?