उत्तर : 2. "138"
व्याख्या :

Answer: B) 138 Explanation: The gram formula mass of a compound is nothing but the molar mass. The molar mass of K2CO3 (Potassium Carbonate) is given by Atomic weights of individual elements are   K (Potassium) = 39 g C (Carbon) = 12 g O (Oxygen) = 16 g   Hence, that of K2CO3 = 39(2) + 12 + 16(3) = 78 + 12 + 48 = 138.