Question

The volume of 10 N and 4 N $HCl$ required to make 1 L of 7 N $HCl$ are:

• A. 0.50 L of 10 N $HCl$ and 0.50 L of 4 N $HCl$
• B. 0.60 L of 10 N $HCl$ and 0.40 L of 4 N $HCl$
• C. 0.80 L of 10 N $HCl$ and 0.20 L of 4 N $HCl$
• D. 0.75 L of 10 N $HCl$ and 0.25 L of 4 N $HCl$

Answer 1

Answer: (A)

0.50 L of 10 N $HCl$ and 0.50 L of 4 N $HCl$

Let $V$ litre of 10 N $HCl$ be mixed with $(1-V)$ litre of 4 N $HCl$ to give$(V+1-V)=1L$ of 7 N $HCl$.

From, $N_1{V}_1+N_2{V}_2=NV$

$10V+4(1-V)=7\times 1$

$10V+4-4V=7$

$6V=7-4$

$V=\frac{3}{6}=0.50L$

Volume of $10NHCl=0.50L$

Volume of $4NHCl=1-0.50=0.50L$

Hence, option A is correct.