What is Baeyer's reagent?

What are $X$ and $Y$ in the following reaction?
$Pent-2-ene \xrightarrow[(ii) Zn / H_2O]{(i) O_3} X + Y$

The reaction conditions used for converting $1, 2$-dibromoethane to ethylene are:

The major products of the following reaction are :

Which of the following alkenes can generate optically active compounds upon hydrogenation?

$17 \, mg$ of a hydrocarbon ($M$.$F$. $C_{10}H_{16}$) takes up $8.40 \, mL$ of $H_2$ gas measured at $0^{\circ}C$ and $760 \, mm$ of $Hg$. Ozonolysis of the same hydrocarbon yields acetone,formaldehyde,and a compound with the structure $CH_3-CO-CH_2-CH_2-CHO$. The number of double bonds present in the hydrocarbon is $...........$.