In brief, state what happens when rheo leaves are boiled in water first and then a drop of sugar syrup is put on it.

An inflated balloon full of air goes down slowly (becomes smaller and smaller slowly) even though the knot at the mouth of the balloon is airtight. And after a week all the air has escaped from the balloon. Explain how the air particles got out of the balloon.

Bromine occurs in nature mainly in the form of two isotopes ${}_{35}{}^{79}\mathrm{Br}$ and  ${}_{35}{}^{81}\mathrm{Br}$. If the abundance of ${}_{35}{}^{79}\mathrm{Br}$ is isotope is $49.7\%$ and that of ${}_{35}{}^{81}\mathrm{Br}$​ isotope is $50.3\%$ calculate the average atomic mass of bromine.