Question

Which of the following ionic species has highest precipitating power?

• A. $\mathrm{Cu^{2+}}$
• B. $\mathrm{SO_4^{2-}}$
• C. $\mathrm{Na^{+}}$
• D. $\mathrm{Al^{3+}}$

Hint:

Higher the charge on an ion, greater is its precipitating power.

Answer 1

The Correct Option is D

Step 1: Meaning of precipitating power.
Precipitating power of an ion depends on its charge and its ability to neutralize oppositely charged ions in solution.

Step 2: Effect of ionic charge.
Ions with higher charge have greater electrostatic attraction and hence greater ability to cause precipitation.

Step 3: Comparison of given ions.
Among the given ions, $\mathrm{Al^{3+}}$ has the highest positive charge, making it most effective in precipitating oppositely charged ions.

Step 4: Conclusion.
Thus, the ionic species with highest precipitating power is (D) $\mathrm{Al^{3+}$}.