`2CHCl_3+O_2 overset(X)(rarr)2COCl_2+2HCl`
In the above reaction, X stands for

Options

A. An oxidant
B. A reductant
C. Light and air
D. None of these

Explanation

To solve the question regarding the reaction \( 2CHCl_3 + O_2 \overset{X}{\rightarrow} 2COCl_2 + 2HCl \), we need to identify what \( X \) represents in this reaction.

### Step-by-Step Solution:

1. **Identify the Reactants and Products**:
- The reactants in the equation are chloroform (\( CHCl_3 \)) and oxygen (\( O_2 \)).
- The products are phosgene (\( COCl_2 \)) and hydrochloric acid (\( HCl \)).

2. **Understand the Reaction Conditions**:
- The reaction involves the conversion of chloroform and oxygen into phosgene and hydrochloric acid.
- This type of reaction typically requires a catalyst or specific conditions to proceed.

3. **Determine the Role of \( X \)**:
- In organic chemistry, certain reactions involving halogenated compounds and oxygen often require the presence of light or heat to facilitate the reaction.
- In this case, the presence of light (or ultraviolet light) is commonly used to initiate reactions involving halogenated hydrocarbons.

4. **Conclude What \( X \) Stands For**:
- Given that this reaction involves the conversion of chloroform in the presence of oxygen, it is likely that \( X \) represents light or ultraviolet light.
- Therefore, \( X \) can be concluded to be "light" or "UV light".

### Final Answer:
\( X \) stands for light (or ultraviolet light).