To find the weight of the gas you need to find the number of moles of using ideal gas formula. Remember to change the temperature unit to Kelvin and the pressure to kpa or atm
PV=nRT
n= PV/RT
n= 699 mmHg* 0.1333kpa * 0.357 L/ 8.314 kpa*L / mol*K * (45 +273.15)K
n=0.012 moles
weight= n * molecular weight
weght= 0.012 *92.448 g/mol= 1.109 grams
