mole caluculation

(a) 1.5 moles of nitrogen dioxide gas contain 1.5 x 6.02 x 1023 = 9.03 x 1023 nitrogen dioxide molevules, meaning that there are 9.03 x 1023 x 3 = 2.709 x 1024 atoms

(b) For each unit of sodium carbonate-10-water, there are 2 Na, 1 C, 3 O atoms and 10 water molecules, giving a total of 36 atoms.

So in 0.5 moles, there are 0.5 x 6.02 x 1023 x 36 = 1.084 x 1025 atoms