Answer to Question #191090 in Chemistry for Saklaj Aamir

Question

 Which of the following gases under identical conditions (temperature, pressure) contains the 

largest number of molecules?

(A) 10 g nitrogen (B) 10 g chlorine (C) 10 g sulphur trioxide

(D) 10 g helium (E) 10 g carbon dioxide

Answer 1

Under identical conditions (temperature, pressure) 1 mole of matter contains the equal number of molecules - 6.022×10^23.

n = m / M

M (N₂) = 28 g/mol

M (Cl₂) = 70.9 g/mol

M (SO₃) = 80.1 g/mol

M (He) = 4 g/mol

M (CO₂) = 44 g/mol

n (N₂) = 10 / 28 = 0.36 mol

n (Cl₂) = 10 / 70.9 = 0.14 mol

n (SO₃) = 10 / 80.1 = 0.13 mol

n (He) = 10 / 4 = 2.5 mol

n (CO₂) = 10 / 44 = 0.23 mol

As 10 g of Helium contains the largest amount of moles - 2.5 moles, it has the largest number of molecules.