Question

$6.023\times 10^{22}$ molecules are present in $10g$ of a substance 'x'. The molarity of a solution containing $5g$ of substance 'x' in $2L$ solution is _____$\times 10^{-3}$

Answer 1

Answer: 25

moles $=\frac{\text{ number of molecules }}{6\times 10^{23}}=\frac{\text{ given mass }}{\text{ molar mass }}$

$\Rightarrow$ molar mass $=\frac{10\times 6.023\times 10^{23}}{6.023\times 10^{22}}=100g/mol$

$\Rightarrow$ molarity $=\frac{\text{ moles of solute }}{{\text{ volume of sol }}^n(\ell )}=\frac{(5/100)}{2}$

$=0.025$