Assertion: Mg gets oxidised when heated in `CO_(2)` atmosphere.
Reason: Mg has a strongly affinity for oxygen.

Options

A. If both assertion and reason are true and the reason is the correct explanation of assertion
B. If both assertion and reason are true and the reason is not the correct explanation of assertion
C. If assertion is false but reason is true
D. If assertion is true but the reason is false

Explanation

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

### Step 1: Analyze the Assertion
The assertion states that "Mg gets oxidised when heated in `CO_(2)` atmosphere."

- When magnesium (Mg) is heated in an atmosphere of carbon dioxide (CO2), it reacts with CO2 to form magnesium oxide (MgO) and carbon (C). This indicates that magnesium is indeed oxidized in this reaction.

### Step 2: Analyze the Reason
The reason states that "Mg has a strong affinity for oxygen."

- Magnesium is known to have a high affinity for oxygen, which means it readily reacts with oxygen to form magnesium oxide. This characteristic is a fundamental property of magnesium, especially at elevated temperatures.

### Step 3: Establish the Relationship
Now, we need to determine if the reason provided correctly explains the assertion.

- Since magnesium does have a strong affinity for oxygen, it supports the assertion that magnesium gets oxidized when heated in a CO2 atmosphere. The reaction can be summarized as:

\[ 2Mg + CO_2 \rightarrow 2MgO + C \]

- This shows that the reason (strong affinity for oxygen) is indeed a correct explanation for the assertion (oxidation of magnesium in CO2).

### Conclusion
Both the assertion and the reason are true, and the reason correctly explains the assertion.

### Final Answer
Both the assertion and reason are true, and the reason is the correct explanation of the assertion.