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?

Chlorine has two isotopes ${ }^{35} \mathrm{Cl}$ and ${ }^{37} \mathrm{Cl}$ with average atomic mass of 35.5 . What is the ratio of their relative abundance respectively?

Calculate mass in kg of $4.48 \mathrm{dm}^3$ carbon dioxide at STP.

What is the volume occupied by 1 molecule of water, if its density is $1 \mathrm{~g} \mathrm{~cm}^{-3}$ ?