When `(NH_(4))_(2)Cr_(2)O_(7)` is heated, the gas evolved is

Options

A. `N_(2)`
B. `NO_(2)`
C. `O_(2)`
D. `N_(2)O`

Explanation

To determine the gas evolved when ammonium dichromate \((NH_4)_2Cr_2O_7\) is heated, we can follow these steps:

### Step 1: Write the decomposition reaction
The first step is to write the balanced equation for the thermal decomposition of ammonium dichromate. When heated, ammonium dichromate decomposes into chromium(III) oxide, water, and nitrogen gas.

\[ (NH_4)_2Cr_2O_7 \xrightarrow{\text{heat}} Cr_2O_3 + H_2O + N_2 \]

### Step 2: Identify the products
From the balanced equation, we can see that the products of the reaction include:
- Chromium(III) oxide \((Cr_2O_3)\)
- Water \((H_2O)\)
- Nitrogen gas \((N_2)\)

### Step 3: Analyze the gases evolved
Among the products, the gas evolved during the heating process is nitrogen gas \((N_2)\).

### Conclusion
Thus, the gas evolved when \((NH_4)_2Cr_2O_7\) is heated is nitrogen gas \((N_2)\).

### Final Answer
The gas evolved is \(N_2\).

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