The molecular mass of sodium oxide (Na2O) is

A. 61.97894.

B. 22.98977.

C. 45.97954.

D. 38.98917.

The molecular mass of sodium oxide (Na2O) is A. 61.97894. The molecular mass of a molecule (Mr) is the sum of atomic masses of its atoms (Ar). The molecular mass of sodium oxide is: Mr (Na2O) = 2 * Ar (Na) + Ar (O). From the periodic table, Ar (Na) = 22.989769 and Ar (O) = 15.9994. The molecular mass of sodium oxide is: Mr (Na2O) = 2 * 22.989769 + 15.9994 = 45.979538 + 15.9994 = 61.97894.