Q2 / 150 · MHT CET 2026 (19 April Shift 1) · Chemistry

What is the pH of solution containing $5 \times 10^{-4}\ \text{M}\ \text{H}^+$ ion?

  • A
    $4.699$
  • Correct answer
    B
    $3.301$
  • C
    $5.401$
  • D
    $3.725$

Solution

The pH of a solution is given by the negative logarithm of the hydrogen ion concentration:

$\text{pH} = -\log[\text{H}^+]$

Given $[\text{H}^+] = 5 \times 10^{-4}\ \text{M}$

$\text{pH} = -\log(5 \times 10^{-4})$

$\text{pH} = -(\log 5 + \log 10^{-4})$

$\text{pH} = -(\log 5 - 4)$

$\text{pH} = 4 - \log 5$

Using the value $\log 5 \approx 0.699$:

$\text{pH} = 4 - 0.699 = 3.301$

Answer: $3.301$

Hence, the correct answer is option: 'B'.

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