Question

The carbonate of a metal is isomorphous with $MgC{O}_3$ and contains $6.091\%$ of carbon. Atomic weight of the metal is nearly:

• A. $48$
• B. $68.5$
• C. $137$
• D. $120$

Answer 1

The correct option is C $137$

The molecular formula of metal carbonate is ${MCO}_3$ as it is isomorphous with ${MgCO}_3$.

Let the mass of metal be $M$. Molecular weight of this carbonate $=(M+12+48)$. Mass percentage of carbon in this compound $=6.091$

$\frac{6.091}{100}\times (M+12+48)=12$

$M=\frac{12\times 100}{6.091}-60$

$M=137$

Atomic wt. of the element is 137.01 amu which is Barium and the metal carbonate is BaCO${}_3$

Hence, the correct option is $C$