Which is the suitable reagent for the above reaction?

What product is formed when $Br_2$ is added to ethylene in the presence of aqueous $NaCl$?

The major product of the following reaction sequence is:

Write $IUPAC$ names of the products obtained by the ozonolysis of the following compounds:
$(i)$ $Pent-2-ene$
$(ii)$ $3,4-Dimethylhept-3-ene$
$(iii)$ $2-Ethylbut-1-ene$
$(iv)$ $1-Phenylbut-1-ene$

Compound $X$ on heating with $Zn$ dust gives compound $Y$,which on treatment with $O_3$ followed by reaction with $Zn$ dust and $H_2O$ gives propionaldehyde. The structure of $X$ is:

Write the major product of the following reaction: $Ph-CH_2-CH=CH_2 \xrightarrow{HBr, \text{Peroxide}}$