Question

The solution having lowest molar concentration is:

• A. $1.0\mathrm{N}\mathrm{HCl}$
• B. $0.4\mathrm{N}{\mathrm{H}}_2{\mathrm{SO}}_4$
• C. $0.1\mathrm{N}{\mathrm{Na}}_2{\mathrm{CO}}_3$
• D. $1\mathrm{N}\mathrm{NaOH}$

Answer 1

The correct option is C

$0.1\mathrm{N}{\mathrm{Na}}_2{\mathrm{CO}}_3$

Explanation for the correct option:

(c ) $0.1\mathrm{N}{\mathrm{Na}}_2{\mathrm{CO}}_3$

• $\mathrm{Molar}\mathrm{concentration}=\frac{\mathrm{Normal}\mathrm{concentration}}{\mathrm{equivalent}\mathrm{factor}}$
• For $1.0\mathrm{N}\mathrm{HCl}$= ${\mathrm{M}}_1=\frac{1}{1}=1\mathrm{M}$
• For $0.4\mathrm{N}{\mathrm{H}}_2{\mathrm{SO}}_4$= ${\mathrm{M}}_2=\frac{0.4}{2}=2\mathrm{M}$
• For $0.1\mathrm{N}{\mathrm{Na}}_2{\mathrm{CO}}_3$ = ${\mathrm{M}}_3=\frac{0.1}{2}=0.05\mathrm{M}$
• For $1\mathrm{N}\mathrm{NaOH}$ = ${\mathrm{M}}_4=\frac{1}{1}=1\mathrm{M}$
• Thus $0.1\mathrm{N}{\mathrm{Na}}_2{\mathrm{CO}}_3$ is having lowest molar concentration
• Hence this option is correct

Explanation for the incorrect options:

(a) $1.0\mathrm{N}\mathrm{HCl}$

• It has the molar concentration equal to $1\mathrm{M}$which is greater than that of $0.1\mathrm{N}{\mathrm{Na}}_2{\mathrm{CO}}_3$
• Thus, this option is incorrect.

(b) $0.4\mathrm{N}{\mathrm{H}}_2{\mathrm{SO}}_4$

• It has the molar concentration equal to $2\mathrm{M}$which is greater than that of $0.1\mathrm{N}{\mathrm{Na}}_2{\mathrm{CO}}_3$
• Thus, this option is incorrect.

(d) $1\mathrm{N}\mathrm{NaOH}$

• It has the molar concentration equal to $1\mathrm{M}$which is greater than that of $0.1\mathrm{N}{\mathrm{Na}}_2{\mathrm{CO}}_3$
• Thus, this option is incorrect.

Hence the correct option is (c ) $0.1\mathrm{N}{\mathrm{Na}}_2{\mathrm{CO}}_3$