text: 1 torr 101325 /760 Pa =133 Pa \n\n825 torrs =133*825 = 1.1* 10^5 Pa\n\ncalculate n  from pV = nRT  in MKSA   R = 8.31JK-1 1l = 10^-3 m^3\n\nn= 1.1 10^5 *10^-3/ 8.31 * ( 273+17)= 0.045mole \nso 0.045 mole weights 6.535\n\nand 1 mole = 6.535 /0.045=144