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)

Let $V$ litre of $10\, N\, HCl$ be mixed with $(1-V)$ litre
of $4\, N\, HCl$ to give $(V+1-V)=1\, L$ of $7\, N\, HCl$.
From, $N_{1} V_{1}+N_{2} V_{2} =N V$
$10\, V+4(1-V) =7 \times 1$
$10\, V+4-4 V =7$
$6\, V =7-4$
$V =\frac{3}{6}=0.50\, L$
Volume of $10\, N\, HCl =0.50\, L$
Volume of $4\, N\, HCl =1-0.50=0.50\, L$