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 NaOHb. 55 mL M/10 HCl + 45 mL M/10 NaOHc. 75 mL M/5 HCl + 25 mL M/5 NaOHd. 100 mL M/10 HCl + 100 mL M/10 NaOHpH…

Following solutions were prepared by mixing different volumes of NaOH and HCl of different concentrations :

a. 60 mL \(\frac{M}{10}\) HCl + 40 mL \(\frac{M}{10}\) NaOH

b. 55 mL \(\frac{M}{10}\) HCl + 45 mL \(\frac{M}{10}\) NaOH

c. 75 mL \(\frac{M}{5}\) HCl + 25 mL \(\frac{M}{5}\) NaOH

d. 100 mL \(\frac{M}{10}\) HCl + 100 mL \(\frac{M}{10}\) NaOH

pH of which one of them will be equal to 1 ?

1. b

2. d

3. a

4. c

Doubtly Asked 30 Oct 2026 NEET UG 2018 Practice test neet Save WhatsApp Report

1 answer

Best answer

Answer: 4. c

pH = 1 means \([\mathrm{H^+}]=0.1\) M, so excess strong acid of that concentration must remain after mixing.

a: HCl 6 mmol, NaOH 4 mmol, excess 2 mmol in 100 mL = 0.02 M, pH about 1.7.
b: 5.5 - 4.5 = 1 mmol in 100 mL = 0.01 M, pH = 2.
c: HCl \(75\times0.2=15\) mmol, NaOH \(25\times0.2=5\) mmol, excess 10 mmol in 100 mL = 0.1 M, pH = 1.
d: exact neutralisation, pH = 7.

So only mixture c gives pH 1.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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