A : Oxides of carbon in higher oxidation state is more acidic than in lower oxidation state .
R : Both `CO_(2)` and CO can exist .

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion , then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion , then mark (2)
C. If Assertion is true statement but Reason is false , then mark (3)
D. If both Assertion and Reason are false statements , then mark (4)

Answer

To solve the question, we need to analyze the assertion and reason provided:

**Assertion (A):** Oxides of carbon in higher oxidation state are more acidic than in lower oxidation state.

**Reason (R):** Both CO₂ and CO can exist.

### Step-by-Step Solution:

1. **Understanding Oxidation States:**
- Carbon can exist in different oxidation states in its oxides. The two common oxides of carbon are carbon dioxide (CO₂) and carbon monoxide (CO).
- In CO₂, carbon has an oxidation state of +4.
- In CO, carbon has an oxidation state of +2.

2. **Acidity of Oxides:**
- Acidity of oxides generally increases with the oxidation state of the central atom. This is because higher oxidation states typically lead to greater positive charge on the central atom, which can stabilize the negative charge of the conjugate base formed after deprotonation.
- Therefore, CO₂ (with carbon in +4 oxidation state) is more acidic than CO (with carbon in +2 oxidation state).

3. **Lewis Acid Concept:**
- Both CO₂ and CO can act as Lewis acids because they can accept a pair of electrons.
- CO₂ has two vacant orbitals (one in the 2s and one in the 2p) when carbon is in the +4 state, making it a stronger Lewis acid compared to CO, which has only one vacant orbital in the +2 state.

4. **Fajan's Rule:**
- According to Fajan's rule, the covalent character of a bond increases with the increase in the charge density of the cation. Since the size of the cation decreases with increasing positive charge, CO₂ (with a smaller cation size due to +4 charge) will have more covalent character than CO (with +2 charge), leading to increased acidity.

5. **Existence of CO and CO₂:**
- The reason states that both CO and CO₂ can exist, which is true. Carbon can form these two oxides due to its tetravalent nature and the ability to utilize its four valence electrons in bonding.

6. **Conclusion:**
- Both the assertion and reason are true. However, the reason does not explain why the assertion is true. The assertion is about the acidity related to oxidation states, while the reason merely states the existence of the two oxides.

### Final Answer:
- The correct option is **B**: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.