Regular use of which of the following fertilizer increases the acidity of soil?

Regular use of which of the following fertilizer increases the acidity of soil?
  1. Potassium nitrate
  2. Urea
  3. Superphosphate of lime
  4. Ammonium sulphate

Solution

$\left(\mathrm{NH}_4\right)_2 \mathrm{SO}_4$ is a salt of strong acid and weak base, on hydrolysis it ill produce $\mathrm{H}^{+}$ion. This will increase the acidity of soil. $\begin{aligned} & \left(\mathrm{NH}_4\right)_2 \mathrm{SO}_4 \longrightarrow 2 \mathrm{NH}_4^{+}+\mathrm{SO}_4^{2-} \\ & \mathrm{NH}_4^{+}+\mathrm{H}_2 \mathrm{O} \rightleftharpoons \mathrm{NH}_4 \mathrm{OH}+\mathrm{H}^{+} \end{aligned}$ Hence, (D) is correct answer.

Asked in: JEE Main 2007

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