Question

Value of pH solution is 4. It indicates that the concentration of hydrogen ions is:

• A. $10^{-4}$ g/l and the solution is acidic
• B. $10^{-4}$ g/l and the solution is alkaline
• C. $10^{-4}$ mg/l and the solution is acidic
• D. $10^{-4}$ mg/l and the solution is alkaline

Hint:

A pH less than 7 indicates an acidic solution, while a pH greater than 7 indicates an alkaline solution.

Answer 1

The Correct Option is A

The pH of a solution is defined as the negative logarithm (base 10) of the concentration of hydrogen ions in the solution: \[ \text{pH} = -\log[\text{H}^+] \] If the pH is 4, we can calculate the concentration of hydrogen ions: \[ [\text{H}^+] = 10^{-\text{pH}} = 10^{-4} \, \text{mol/l} \] The concentration of hydrogen ions is $10^{-4}$ mol/l, which corresponds to $10^{-4}$ g/l when considering the molar mass of hydrogen ions. Since the pH is less than 7, the solution is acidic.
Therefore, the concentration of hydrogen ions is $10^{-4}$ g/l, and the solution is acidic.