A Colorless solid `A` liberates a brown gas `B` on acidification, a colorless alkaline gas `(C)`on treatment with `NaOH` and a colorless non-reactive gas `D` on heating. If heating of the solid is continued, it completely disappears.
The compound `A` is

Options

A. `NH_(4)NO_(2)`
B. `PH_(4)NO_(3)`
C. `NH_(4)NO_(3)`
D. none of these

Explanation

To solve the problem, we need to identify the colorless solid `A` based on the reactions it undergoes when treated with different substances. Let's break down the information given step by step.

### Step 1: Identify the reactions of solid A
- **Observation 1**: Solid `A` liberates a brown gas `B` upon acidification.
- **Observation 2**: Solid `A` liberates a colorless alkaline gas `C` when treated with `NaOH`.
- **Observation 3**: Solid `A` liberates a colorless non-reactive gas `D` upon heating, and if heating continues, it completely disappears.

### Step 2: Analyze the brown gas `B`
The brown gas `B` is likely nitrogen dioxide (NO₂), which is a common brown gas produced from the decomposition of certain nitrogen-containing compounds when they react with acids.

### Step 3: Analyze the alkaline gas `C`
The colorless alkaline gas `C` is likely ammonia (NH₃). Ammonia is a well-known alkaline gas that can be produced from the reaction of ammonium salts with strong bases like sodium hydroxide (NaOH).

### Step 4: Analyze the non-reactive gas `D`
The colorless non-reactive gas `D` is likely nitrogen (N₂). Nitrogen is a colorless, non-reactive gas that can be produced from the thermal decomposition of ammonium nitrate (NH₄NO₂).

### Step 5: Identify solid `A`
Given the observations and the gases produced, we can deduce that solid `A` is likely ammonium nitrite (NH₄NO₂). Here’s how:
- When ammonium nitrite is treated with an acid (e.g., HCl), it produces nitrogen dioxide (NO₂) and water.
- When ammonium nitrite is treated with NaOH, it releases ammonia (NH₃).
- Upon heating, ammonium nitrite decomposes to produce nitrogen gas (N₂) and water, which explains the disappearance of solid `A`.

### Conclusion
The compound `A` is ammonium nitrite (NH₄NO₂).

### Summary of the Solution
1. **Identify the gases produced**:
- Brown gas `B` is NO₂.
- Alkaline gas `C` is NH₃.
- Non-reactive gas `D` is N₂.
2. **Determine the identity of solid `A`**:
- Solid `A` is ammonium nitrite (NH₄NO₂).