a) (8.418x10^24) atoms X 1 mol K/ 6.022x10^23 atoms = 13.98 mol K
4(13.98) = 55.92 mol K2S
55.92 mol K2S X 110.09g/1 mol K2S = 6156 g K2S
b)38.0L CCL4 X 1 mol CCL4 / 22.4 L CCL4 =1.70 mol CCL4
c) 20.8L CO X 1 mol CO / 22.4 L C) = .929 mol CO
.929 mol CO / 2 = .465 mol 02 = 2.79 x 10^23 atoms O2
