1) 1 g of a carbonate (M2CO3) on treatment with excess HCl produces 0.01186 mole of CO2 . The molar mass M2CO3 in g mol-1 is A) 1186 B) 84.3 C) 118.6 D) 11.86 Answer: Option BExplanation:$M_{2}CO_{3}+2HCl\rightarrow 2MCl+H_{2}O+CO_{2}$ 1g 0.01186 mole Number of moles of M2CO3 reacted = Number of moles of CO2 evolved $\frac{1}{M}=$ 0.01186 [M = Molar mass of M2CO3] $M=\frac{1}{0.01186}=84.3 g mol^{-1}$