The stability order of the given alkenes is

The addition of $HI$ to the double bond of propene gives isopropyl iodide as the major product because the addition proceeds through:

The correct stability order of alkyl substituted alkenes is

An alkene $X$ $(C_4H_8)$ exhibits geometrical isomerism. Oxidation of $X$ with $KMnO_4 | H^+$ gives $Y$. On heating the sodium salt of $Y$ with a mixture of $NaOH$ and $CaO$,$Z$ is obtained. What is $Z$?

Give the increasing order of stability for the following alkenes based on their heat of hydrogenation $(\Delta H^o)$:
$(I) (CH_3)_2C = C(CH_3)_2$
$(II) CH_3CH_2CH_2CH = CH_2$
$(III) (CH_3)_2C = CHCH_3$
$(IV) CH_3CH_2C(CH_3) = CH_2$

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