Assertion: In the reaction :
`MnO_(2) +4HCl to MnCl_(2) +2H_(2)O +Cl_(2)`
HCl is getting oxidized while `MnO_(2)` is getting reduced.
Reason: The process in which oxygen is added to a substance is called oxidation.
whereas the process in which oxygen is removed from a substance is called reduction.

Options

A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true but R is NOT the correct explanation of A.
C. A is true but R is false.
D. A is false and R is true.

Explanation

To analyze the given assertion and reason, let's break down the chemical reaction and the concepts of oxidation and reduction step by step.

### Step 1: Write the balanced chemical equation
The reaction provided is:
\[ \text{MnO}_2 + 4\text{HCl} \rightarrow \text{MnCl}_2 + 2\text{H}_2\text{O} + \text{Cl}_2 \]

### Step 2: Identify oxidation and reduction
- **Oxidation** is defined as the loss of electrons or an increase in oxidation state, which can also involve the addition of oxygen or the removal of hydrogen.
- **Reduction** is defined as the gain of electrons or a decrease in oxidation state, which can involve the removal of oxygen or the addition of hydrogen.

### Step 3: Determine the oxidation states
- In \(\text{MnO}_2\), manganese (Mn) has an oxidation state of +4.
- In \(\text{MnCl}_2\), manganese (Mn) has an oxidation state of +2.
- In \(\text{HCl}\), chlorine (Cl) has an oxidation state of -1, and in \(\text{Cl}_2\), chlorine (Cl) has an oxidation state of 0.

### Step 4: Analyze the changes in oxidation states
- **MnO2 to MnCl2**: The oxidation state of Mn decreases from +4 to +2, indicating that MnO2 is being reduced (gaining electrons).
- **HCl to Cl2**: The oxidation state of Cl increases from -1 in HCl to 0 in Cl2, indicating that HCl is being oxidized (losing electrons).

### Step 5: Conclusion on assertion and reason
- The assertion states that HCl is getting oxidized while MnO2 is getting reduced, which is correct based on the analysis.
- The reason states that the process of adding oxygen is called oxidation and removing oxygen is called reduction. This is partially correct but does not encompass all definitions of oxidation and reduction, especially in terms of electron transfer.

### Final Statement
Both the assertion and the reason are true. The assertion correctly identifies the oxidation and reduction processes occurring in the reaction, while the reason provides a basic definition of oxidation and reduction. However, the reason does not fully explain the assertion since it does not mention the electron transfer aspect.