$250 \mathrm{~mL}$ of a sodium carbonate solution contains $2.65 \mathrm{~g}$ of $\mathrm{Na}_{2}…

$250 \mathrm{~mL}$ of a sodium carbonate solution contains $2.65 \mathrm{~g}$ of $\mathrm{Na}_{2} \mathrm{CO}_{3}$. If $10 \mathrm{~mL}$ of this solution is diluted to one litre, what is the concentration of the resultant solution? (mol. wt. of $\mathrm{Na}_{2} \mathrm{CO}_{3}=106$)
  1. $0.1 \mathrm{M}$
  2. $0.01 \mathrm{M}$
  3. $0.001 \mathrm{M}$
  4. $10^{-4} \mathrm{M}$

Solution

Molarity
$=\frac{\mathrm{Wt} \times 1000}{\mathrm{MW} \times \mathrm{V}}=\frac{2.65 \times 1000}{106 \times 250}=0.1 \mathrm{M}$
$\mathrm{M}_{1} \mathrm{~V}_{1}=\mathrm{M}_{2} \mathrm{~V}_{2}$
$\therefore 10 \times 0.1=1000 \times \mathrm{M}_{2}=0.001 \mathrm{M}$ /

Asked in: JEE-TOPICTESTS-CHEMISTRY

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