UPTET Paper 2 Math and Science 2016 Solved Paper

Concept:The number of moles is found by dividing the given mass by the molar mass of the compound. Explanation:First, calculate the molar mass of $SO_2$. One sulfur atom has atomic mass 32 g/mol, and two oxygen atoms have atomic mass 2 × 16 = 32 g/mol. So molar mass = 32 + 32 = 64 g/mol. Given mass is 128 g. Number of moles = $\frac{\text{Given mass}}{\text{Molar mass}} = \frac{128}{64} = 2$ moles. Thus, 128 g of $SO_2$ contains 2 moles. Answer:B. 2 mole