Answer
a) mass increases
b) $1.72\times 10^{-14}Kg$
Work Step by Step
(a) we know that when the temperature increases, then the energy of the system increases as well and according to Einstein's mass-energy relation, the mass of the system increases.
(b) We know that
$\Delta m=\frac{\frac{3}{2}nR\Delta t}{c^2}$
We plug in the known values to obtain:
$\Delta m=\frac{\frac{3}{2}(2.00mol)(8.314J/mol.K)(62.22K)}{(3\times 10^8m/s)^2}$
$\Delta m=1.72\times 10^{-14}Kg$
