Which of the following has the lowest value of Ksp at ordinary temperature is?

Options

A. `Mg(OH)_(2)`
B. `Ca(OH)_(2)`
C. `Ba(OH)_(2)`
D. `Be(OH)_(2)`

Answer

To determine which of the compounds has the lowest value of Ksp (solubility product constant) at ordinary temperature, we can analyze the compounds given: magnesium hydroxide (Mg(OH)₂), calcium hydroxide (Ca(OH)₂), barium hydroxide (Ba(OH)₂), and beryllium hydroxide (Be(OH)₂).

### Step-by-Step Solution:

1. **Understand Ksp**:
Ksp is a measure of the solubility of a compound in water. A lower Ksp value indicates that the compound is less soluble in water.

2. **Identify the Compounds**:
The compounds we are comparing are:
- Magnesium hydroxide (Mg(OH)₂)
- Calcium hydroxide (Ca(OH)₂)
- Barium hydroxide (Ba(OH)₂)
- Beryllium hydroxide (Be(OH)₂)

3. **Consider the Electronegativity**:
The electronegativity of the metal ions affects the solubility of their hydroxides. The order of electronegativity for the metals in these hydroxides is:
- Beryllium (Be) > Magnesium (Mg) > Calcium (Ca) > Barium (Ba)

4. **Analyze the Tendency to Lose OH⁻ Ions**:
The tendency of these hydroxides to lose OH⁻ ions is inversely related to their electronegativity. Thus, the order of tendency to lose OH⁻ ions is:
- Barium hydroxide (Ba(OH)₂) > Calcium hydroxide (Ca(OH)₂) > Magnesium hydroxide (Mg(OH)₂) > Beryllium hydroxide (Be(OH)₂)

5. **Determine Ksp Values**:
Since beryllium hydroxide has the highest electronegativity, it has the least tendency to lose OH⁻ ions, which means it is the least soluble. Therefore, it will have the lowest Ksp value among the four hydroxides.

6. **Conclusion**:
Based on the analysis, beryllium hydroxide (Be(OH)₂) has the lowest value of Ksp at ordinary temperature.

### Final Answer:
Beryllium hydroxide (Be(OH)₂) has the lowest value of Ksp at ordinary temperature.

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