Which of the following alkenes does $\underline{NOT}$ exhibit cis-trans isomerism?

$but-2-yne$ is reacted separately with one mole of $H_2$ as shown below:
$\underline{ B } \xleftarrow[\text{liq } NH_3]{Na} CH_3-C \equiv C-CH_3 \xrightarrow[\Delta]{Pd/C} \underline{ A }$
Identify the incorrect statements from the options given below:
$A.$ $A$ is more soluble than $B$.
$B.$ The boiling point and melting point of $A$ are higher and lower than $B$ respectively.
$C.$ $A$ is more polar than $B$ because dipole moment of $A$ is zero.
$D.$ $Br_2$ adds easily to $B$ than $A$.

Identify the species $X$ in the reaction: $CH_3-CH=CH_2 + [O] \xrightarrow{\text{conc. acidic } KMnO_4} X + HCOOH$

$CH_3-CH_2-CH=CH_2 \xrightarrow[CCl_4]{Br_2} \text{Product}$

Isopropyl alcohol is obtained by reacting which of the following alkenes with conc. $H_2SO_4$ and $H_2O$?

Hardening of oil is done by