Question

10 mL of a solution of $NaOH$ is found to be completely neutralized by 8 mL of a given solution of HCl. 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) 8 mL

(c) 12 mL

(d) 16 mL

Answer 1

Option (d) 16 ml
Using the unitary method,

$\left[\begin{array}{cc}NaOH& HCl\\ 10& 8\\ 20& x\end{array}\right]$

HCl needed for neutralizing 20ml of $NaOH$, $x=\frac{20\times 8}{10}=16mL$