In the given reaction `HCOONaoverset(400^@C)rarr(X)+(Y)`, (X) and (Y) will be

Options

A. `{:(COONa),(|),(COOH):}and H_2`
B. `{:(COONa),(|),(COONa):}and H_2`
C. `{:(COONa),(|),(COONa):}and H_2O`
D. `{:(COOH),(|),(COOH):}and H_2`

Answer

To solve the question regarding the decomposition of sodium formate (HCOONa) when heated to 400°C, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactant**: The reactant given in the question is sodium formate, which has the chemical formula HCOONa.

2. **Understand the Reaction Conditions**: The reaction occurs upon heating sodium formate to a high temperature of 400°C.

3. **Determine the Products**: When sodium formate is heated, it undergoes thermal decomposition. The products of this decomposition reaction are sodium oxalate (C2O4Na2) and hydrogen gas (H2).

4. **Write the Balanced Reaction**: The balanced equation for the decomposition of sodium formate can be represented as:
\[ 2 \, \text{HCOONa} \, \xrightarrow{400^\circ C} \, \text{C}_2\text{O}_4\text{Na}_2 + \text{H}_2 \]
Here, sodium oxalate (C2O4Na2) is formed along with the release of hydrogen gas (H2).

5. **Identify X and Y**: From the balanced equation, we can identify:
- (X) = Sodium Oxalate (C2O4Na2)
- (Y) = Hydrogen Gas (H2)

6. **Conclusion**: Therefore, the products of the reaction when sodium formate is heated to 400°C are sodium oxalate and hydrogen gas.

### Final Answer:
(X) = Sodium Oxalate (C2O4Na2)
(Y) = Hydrogen Gas (H2)