In the reaction, `M + CO_(2) to MO_(2)` (superoixde) the metal M is :

Options

A. `Li`
B. `Na`
C. K
D. `Ba`

Explanation

To determine the metal \( M \) in the reaction \( M + CO_2 \rightarrow MO_2 \) (where \( MO_2 \) is a superoxide), we can follow these steps:

### Step 1: Understand the Reaction
The reaction involves a metal \( M \) reacting with carbon dioxide \( CO_2 \) to form a superoxide \( MO_2 \). Superoxides are compounds that contain the superoxide ion \( O_2^- \).

**Hint:** Recall that superoxides are typically formed by certain alkali metals.

### Step 2: Identify the Type of Metals Involved
Superoxides are primarily formed by alkali metals and some alkaline earth metals. The alkali metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). The alkaline earth metals include barium (Ba), strontium (Sr), and calcium (Ca).

**Hint:** Focus on the alkali metals when considering which metal can form superoxides.

### Step 3: Analyze the Options
Given the options (let's assume they are Li, Na, K, and Ba), we can eliminate barium because it is an alkaline earth metal and does not form superoxides with \( CO_2 \).

**Hint:** Remember that alkaline earth metals typically do not form superoxides.

### Step 4: Compare the Alkali Metals
Among the alkali metals, we need to determine which one has the highest tendency to form superoxides. The tendency to form superoxides increases as we move down the group in the periodic table due to the increasing size of the metal ion.

**Hint:** Think about the periodic trend and which alkali metal is larger and more reactive.

### Step 5: Conclusion
- Lithium and sodium can form peroxides but not superoxides as readily as potassium.
- Potassium (K) is the largest among the alkali metals listed and has the greatest tendency to form superoxides.

Thus, the metal \( M \) in the reaction \( M + CO_2 \rightarrow MO_2 \) is **potassium (K)**.

**Final Answer:** The metal \( M \) is **potassium (K)**.