Boron has two isotopes with atomic masses $10$ and $11$. If its average atomic mass is $10.81$, the abundance of lighter isotope is _____.

At constant temperature, the pressure of $22.4 {\mathrm{dm}}^{\mathrm{3}}$ volume of an ideal gas is increased from $105 \mathrm{kPa}$ to $210 \mathrm{kPa}$, new volume of the gas is _____.