Question

A solution contains $200$ g ppm $CaC{O}_3$. If the value of this concentration in millimoles per gram is $2\times {10}^{-x}$, then the value of $x$ is

Answer 1

Given $200g$ of $CaC{O}_3$ parts per million Solution (out of ${10}^{6}g$ solution).
$=\frac{200}{100}$moles $CaC{O}_3$per million gram.

$=2$ moles $CaC{O}_3$ per million gram.
$=2000$ millimoles $CaC{O}_3$ per million gram.

$⟹$$\frac{2000}{{10}^6}=2\times {10}^{-3}$ millimoles per gram.
So, value of $x$ is $3$.