Question

The volume respectively of 10 N and 4 N HCl required to make 1 L of 7 N HCl respectively are
A. 0.75 L of 10 N HCl and 0.25 L of 4N HCl
B. 0.50 L of 10N HCl and 0.50 L of 4 N HCl
C. 0.65 L pof 10 N HCl and 0.35 L of 4N HCl
D. 0.85 L of 10 N HCl and 0.15 L of 4 N HCl

Answer 1

b) Let, V litre of 10 N HCl be mixed with (1-V) litre of 4N HCl to give ( V+1-V) = 1L of 7 N HCl
As we know that, `N_(1)V_(1)+ N_(2)V_(2) = NV`
10V + 4(1-V) = 7 xx1
10 V + 4-4V = 7, 6V = 7-4, V=3/6 = 0.50 L
Volume of 10 N HCl = 0.50 L
Volume of 4N HCl = 1-0.50 =0.50 L