Correct Answer - Option 2 : 25 ml
Concept:
The reaction of HCl with Na2CO3 is as follows:
2HCl + Na2CO3 → 2NaCl + H2O + CO2
We know that, Meq of HCl = Meq of Na2CO3
\(\frac{{25}}{{1000}} \times 1 \times {M_{{\rm{HCl}}}} = \frac{{30}}{{1000}} \times 0.1 \times 2\)
\({M_{{\rm{HCl}}}} = \frac{{30 \times 0.2}}{{25}} = \frac{6}{{25}}{\rm{M}}\)
The reaction of HC with NaOH is as follows:
NaOH + HC → NaC + H2O
Also, Meq of HCl = Meq of NaOH
\(\frac{6}{{25}} \times 1 \times \frac{V}{{1000}} = \frac{{30}}{{1000}} \times 0.2 \times 1\)
V = 25 ml.