Alkali metals oxide are obtained by combustion of the metals.Although Na normally gives `Na_2O_2`,it will take up further oxygen at elevated pressure and temperature to form `NaO_2`.The per and superoxides of the heavier alkalies can also be prepared by passing stoichiometric amounts of oxygen into their solution in liquid ammonia.
The different alkali metal oxides can be distinguished by reaction with water.The superoxides reacts with `CO_2` and give oxygen gas.The stability of per and superoxides is based upon that larger cation can stablise larger anion, due to larger lattice energy.
Alkali metals dissolve in liquid ammonia.Dilute solutions are dark blue in colour but as the concentration increases above 3M, the colour changes to copper bronze and the solution acquires the metallic lusture due to the formation of metal ions clusters.The solutions of alkali metals in liquid ammonia are good conductors of electricity due to the presence of ammoniated cations and ammoniated electrons.However, the conductivity decreases as the concentrations increases, since ammoniated electrons and ammoniated cation associate.
`KO_2` is used in oxygen cylinders in space and submarines
because it :

Options

A. Eliminates moisture
B. Absorbs `CO_2` only
C. Absorbs `CO_2` and increases `O_2` contents
D. Products ozone

Explanation

To answer the question regarding why KO2 (potassium superoxide) is used in oxygen cylinders in space and submarines, we can break down the information provided in the video transcript into a step-by-step explanation.

### Step-by-Step Solution:

1. **Understanding KO2**:
- KO2 is potassium superoxide, which is known for its ability to react with carbon dioxide (CO2) and produce oxygen (O2).

2. **Reactions with Water**:
- When KO2 reacts with water, it produces potassium hydroxide (KOH) and oxygen gas (O2). The reaction can be represented as:
\[ 4 KO_2 (s) + 2 H_2O (l) \rightarrow 4 KOH (aq) + 3 O_2 (g) \]
- This reaction shows that KO2 can generate oxygen when it comes into contact with moisture, which is essential in confined spaces like submarines and space shuttles.

3. **Absorption of CO2**:
- KO2 can also react with CO2, which is a byproduct of respiration. The reaction can be represented as:
\[ 4 KO_2 (s) + 2 CO_2 (g) \rightarrow 2 K_2CO_3 (s) + 3 O_2 (g) \]
- This reaction indicates that KO2 not only produces oxygen but also absorbs CO2, helping to maintain a breathable atmosphere.

4. **Role in Regenerating Atmosphere**:
- In a closed environment like a submarine or spacecraft, the air can become depleted of oxygen and enriched with CO2 due to human respiration. KO2 helps to regenerate the atmosphere by releasing oxygen and removing CO2.

5. **Conclusion**:
- Therefore, KO2 is used in oxygen cylinders in space and submarines because it absorbs CO2 and produces oxygen, which is crucial for sustaining life in these enclosed environments.

### Final Answer:
KO2 is used in oxygen cylinders in space and submarines because it absorbs CO2 and produces O2, thereby helping to maintain a breathable atmosphere.

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