Which of the following compound are called unsaturated
compounds `-` that is , it /they add /s `H_(2)` catalytically at ordinary condition of temperature ?

Options

A.
B.
C.
D.

Explanation

To determine which of the given compounds are unsaturated compounds that can add hydrogen (H₂) catalytically at ordinary temperatures, we need to understand the definitions and characteristics of saturated and unsaturated compounds.

### Step-by-Step Solution:

1. **Identify the Types of Compounds**:
- Unsaturated compounds contain at least one double bond (alkenes) or triple bond (alkynes) in their structure.
- Saturated compounds, on the other hand, contain only single bonds (alkanes).

2. **Examine the Given Compounds**:
- Look at the structures provided in the question. Identify if they are alkenes, alkynes, or alkanes.
- For example, if one of the compounds is cyclohexene, it has a double bond and is classified as an unsaturated compound.

3. **Understanding Catalytic Hydrogenation**:
- Catalytic hydrogenation is a process where hydrogen is added to a compound in the presence of a catalyst (usually metals like palladium, platinum, or nickel).
- Unsaturated compounds can undergo this reaction to become saturated by breaking the double or triple bonds and adding hydrogen atoms.

4. **Determine Which Compounds Can Undergo Hydrogenation**:
- If a compound has a double bond (like cyclohexene), it can react with H₂ to form a saturated compound (cyclohexane).
- Compounds that do not have double or triple bonds (like cyclohexane) cannot undergo this reaction as they are already saturated.

5. **Conclusion**:
- Based on the analysis, the compound that can add hydrogen catalytically is the one that is unsaturated.
- In this case, if cyclohexene is among the options, it is the correct answer as it can undergo catalytic hydrogenation.

### Final Answer:
The unsaturated compound that can add H₂ catalytically at ordinary conditions is **option A (cyclohexene)**.