If we take 20 ml of the same solution of NaOH, the amount of HCl solution (the same solution as before) required to neutralize it will be :

(a) 4 ml   (b) 8ml

(c)12 ml  (d) 16ml

Option (d) is the answer.

It is assumed that 10 mL of NaOH solution is totally neutralized by 8 mL of HCl solution. Then 20ml of NaOH solution, which is double the amount used previously, will require double the amount of HCl solution used previously. That’s 16ml that needs to be neutralized totally.