NEET2018ChemistryIonic EquilibriumActual
Following solutions were prepared by mixing different volumes of NaOH and HCl of different concentrations. (i) 60   mL M 10   HCl + 40 mL M 10 NaOH (ii) 55   mL M 10 HCl + 45 mL M 10 NaOH (iii) 75   mL M 5 HCl + 25 mL M 5 NaOH (iv) 100   mL M 10 HCl + 100   mL M 10 NaOH The pH of which one of them will be equal to 1 ?
Options
- A(iv)
- B(i)
- C(ii)
- D(iii)
Correct answer
D. (iii)
Step-by-step solution
Equivalent of acid = N 1 V 1 Equivalent of base = N 2 V 2 As N 1 V 1 > N 2 V 2 , acid is left at the end of the reaction. The 'n' factor of NaOH and HCl are 1 , 1 . So, N = M for both. N final   solution = H + = N 1 V 1 - N 2 V 2 V 1 + V 2 = 1 5 × 75 - 1 5 × 25 75 + 25 = 1 10 = 10 − 1