Alkenes usually show which type of reaction?

What is the product of the following reaction?
$1,2-\text{dimethylcyclopentene} \xrightarrow[2. NaHSO_3]{1. OsO_4} \text{Product}$

In the following reaction sequence,what are $A$ and $R$ respectively?
$CH_2 = CH_2$ $\xrightarrow{HOCl} A$ $\xrightarrow{R} \begin{array}{c} CH_2OH \\ | \\ CH_2OH \end{array}$

Which of the following alkenes reacts fastest with $H_2$ under catalytic hydrogenation conditions?

Arrange the following alkenes in increasing order of their enthalpy of hydrogenation $(-\Delta H)$:

Identify the major product $X$ in the following reaction:
$C_6H_5-CH_2-CH=CH_2 \xrightarrow{HBr, R_2O_2} X$