Which compound will liberate oxygen when reacts with ice cold water ?

Options

A. `Na_2O_2`
B. `KO_2`
C. `Na_2O`
D. `Cs_2O_2`

Answer

To solve the question of which compound liberates oxygen when it reacts with ice-cold water, we need to analyze the reactions of the given compounds with water.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given in the options are Na2O2, KO2, Na2O, and CS2O2.

2. **React Na2O2 with Water**:
- Reaction:
\[ \text{Na}_2\text{O}_2 + 2 \text{H}_2\text{O} \rightarrow 2 \text{NaOH} + \text{H}_2\text{O}_2 \]
- Result: This reaction produces sodium hydroxide (NaOH) and hydrogen peroxide (H2O2) but does not liberate oxygen.

3. **React KO2 with Water**:
- Reaction:
\[ 2 \text{KO}_2 + 2 \text{H}_2\text{O} \rightarrow 2 \text{KOH} + \text{H}_2\text{O}_2 + \text{O}_2 \]
- Result: This reaction produces potassium hydroxide (KOH), hydrogen peroxide (H2O2), and liberates oxygen (O2).

4. **React Na2O with Water**:
- Reaction:
\[ \text{Na}_2\text{O} + \text{H}_2\text{O} \rightarrow 2 \text{NaOH} \]
- Result: This reaction produces sodium hydroxide (NaOH) and does not liberate oxygen.

5. **React CS2O2 with Water**:
- Reaction:
\[ \text{CS}_2\text{O}_2 + 2 \text{H}_2\text{O} \rightarrow 2 \text{CSOH} + \text{H}_2\text{O}_2 \]
- Result: This reaction produces carbon disulfide hydroxide (CSOH) and hydrogen peroxide (H2O2) but does not liberate oxygen.

6. **Conclusion**: Based on the reactions analyzed, only KO2 liberates oxygen when it reacts with ice-cold water. Therefore, the correct answer is **Option B (KO2)**.