Following solutions were prepared by mixing different volumes of NaOH and HCl of different concentrations:
a. 60 mL `(M)/(10) HCl + 40 mL (M)/(10)` NaOH
b. 55 mL `(M)/(10) HCl + 45 mL (M)/(10)` NaOH
c.75 mL `(M)/(5) HCl + 25 mL (M)/(5)` NaOH
d. 100 mL `(M)/(10) HCl + 100 mL (M)/(10)` NaOH
pH of which one of them will be equal to 1 ?

Options

A. (ii)
B. (i)
C. (iv)
D. (iii)

Answer

D

Explanation

`NaOH + HCl to NaCl +H_(2)O`
`{:(25mL M/5,75mL M/5),(25 xx 1/5,75xx1/5),(rArr5"m mol",rArr15"m mol"):}`
On complete neutralisation
`[H^(+)] = (10 " m mol")/(75 +25 mL) = 0.1 m `
pH = 1