Question

The volumes of $4$ N HCl and $10$ N HCl required to make $1$ litre of $6$ N HCl are:

• A. $0.75$ litre of $10$ N HCl and $0.25$ litre of $4$ N HCl
• B. $0.25$ litre of $4$ N HCl and $0.75$ litre of $10$ N HCl
• C. $0.67$ litre of $4$ N HCl and $0.33$ litre of $10$ N HCl
• D. $0.80$ litre of $4$ N HCl and $0.20$ litre of $10$ N HCl

Answer 1

The correct option is C $0.67$ litre of $4$ N HCl and $0.33$ litre of $10$ N HCl

Let $N_1$ and $V_1$ be normality and volume of $4NHCl$ and $N_2$ be normality and volume of $10NHCl$ respectively.

As volume to make is $1L$ and Normality to make is $6N$,

so $V_1+V_2=V$

As we know $N_1{V}_1+N_2{V}_2=NV$

Calculation to determine $V_1$ and $V_2$:

Substituting the values in $N_1{V}_1+N_2{V}_2=NV$ equation

$4\times V_1+10\times (1-V_1)=6\times 1$ ( As $V_2=1-V_1$)

so $V_1=2/3$ and $V_2=1/3$

$V_1=2/3=\mathrm{0..67}$ litre and $V_2=0.33$ litre

Thus, answer is $0.67$ litre of $4NHCl$ and $0.33$ litre of $10NHCl$.

Hence, the correct option is $C$