Compound which on heating produces paramagnetic acidic gas?

Options

A. `Mg(NO_(3))_(2)`
B. `Fe_(2)(SO_(4))_(3)`
C. `FeCO_(3)`
D. `HgC_(2)O_(4)`

Explanation

To solve the question of which compound produces a paramagnetic acidic gas upon heating, we can follow these steps:

### Step 1: Understand the Definition of Paramagnetic
Paramagnetic substances are those that have unpaired electrons, resulting in a net magnetic moment. A gas is considered paramagnetic if it has an odd number of total valence electrons.

### Step 2: Analyze Each Compound
We will analyze each of the four compounds given in the question to determine if they produce a paramagnetic acidic gas when heated.

1. **Magnesium Nitrate (Mg(NO3)2)**
- Upon heating, magnesium nitrate decomposes into magnesium oxide (MgO), nitrogen dioxide (NO2), and oxygen (O2).
- The gas produced is NO2.
- NO2 has an odd number of total valence electrons (5 from nitrogen + 12 from two oxygens = 17), making it paramagnetic.
- NO2 is also acidic as it can react with water to form nitric acid (HNO3).

2. **Ferric Sulphate (Fe2(SO4)3)**
- When heated, ferric sulfate decomposes into ferric oxide (Fe2O3) and sulfur trioxide (SO3).
- SO3 has an even number of total valence electrons (6 from sulfur + 18 from three oxygens = 24), making it diamagnetic.
- SO3 is acidic but does not meet the paramagnetic criterion.

3. **Ferrous Carbonate (FeCO3)**
- Upon heating, ferrous carbonate decomposes into ferric oxide (Fe3O4), carbon dioxide (CO2), and carbon monoxide (CO).
- CO2 is diamagnetic (even number of total valence electrons) and acidic, while CO is neutral.
- Neither gas produced is paramagnetic.

4. **Mercuric Oxalate (HgC2O4)**
- When heated, mercuric oxalate decomposes into mercury (Hg) and carbon dioxide (CO2).
- CO2 is also diamagnetic and acidic.
- Thus, this compound does not produce a paramagnetic gas.

### Step 3: Conclusion
From the analysis, the only compound that produces a paramagnetic acidic gas upon heating is **Magnesium Nitrate (Mg(NO3)2)**, which releases nitrogen dioxide (NO2).

### Final Answer
The compound which on heating produces a paramagnetic acidic gas is **Magnesium Nitrate (Mg(NO3)2)**.

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