Answer
See answers.
Work Step by Step
a. Use the ideal gas law to calculate the volume. Absolute pressure must be used in this model.
$$PV=nRT$$
$$V=\frac{nRT}{P}=\frac{(16.00\;mol)(8.314)(283.15K)}{(1.350atm)(1.013\times10^5\;Pa/atm)}=0.2754\;m^3$$
b. The amount of gas is unchanged. PV/T stays constant.
$$\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}$$
$$T_2=T_1\frac{P_2V_2}{P_1V_1}$$
$$ =(283.15\;K)\frac{2.00atm}{1.350atm}\frac{1}{2}=210\;K=-63^{\circ}$$