What is the product obtained when phenylethene is treated with $\mathrm{KMnO}_4$ in dilute $\mathrm{H}_2 \mathrm{SO}_4$ ?

What is the pH of $10^{-8} \mathrm{M~HCl}$ solution?

What is the oxidation state of iodine in $\mathrm{I}_2 \mathrm{Cl}_6$ ?

Chlorine exists in two isotopic forms ${ }^{35} \mathrm{Cl},{ }^{37} \mathrm{Cl}$. If average atomic mass of chlorine is 35.5 , what is the percentage abundance of these isotopes respectively?