Question

The volume of water to be added to 400ml of N/8 HCI to make it exactly N/12 is

Answer 1

According to this equation
N V = N V we can arrive to the answer
(1/8)*400 = (1/12)*(V(ml))
50 * 12 = V(ml)
600 = V(ml)
Volume added = 600 ml - 400ml = 200 ml
Ans: 200 ml

Answer 2

Let the initial concentration of HCL solution be N₁ and  volume of solution V₁ and  final concentration be  N₂ and  volume of solution V₂

Given,

N₁ = 1/8

N₂ = 1/12 (deci-normal)

V₁ = 400 ml

V₂ = ?

We know that,

$N_1V_1=N_2V_2\\\\\frac{1}{8}\times400=\frac{1}{12}V_2\\\\V_2=600ml$

Final volume  of  solution = 600 ml

Volume  of  added  water  = 600 - 400

                                            = 200 ml