The first element of group different form its congeners, i.e. other members of the group in many ways. These differences may be
due to the following:
i. Small size of atom and ion.
ii. High electronegativity.
iii. Non-availability of low lying d-orbitals.
The first element of a group shows resemblance with the second element of the adjacent group on the right. This is known as
diagonal relationship.
On heating which of the following gives `NO_(2)` ?

Options

A. `NaNO_(3)`
B. `LiNO_(3)`
C. `NH_(4)NO_(3)`
D. `NH_(4)NO_(2)`

Explanation

To solve the question regarding which compound gives NO₂ upon heating, we need to analyze the thermal decomposition of the given nitrates. Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Compounds
The question involves several compounds, specifically nitrates. The compounds we need to consider are:
1. NaNO₃ (Sodium Nitrate)
2. LiNO₃ (Lithium Nitrate)
3. NH₄NO₃ (Ammonium Nitrate)
4. NH₄NO₂ (Ammonium Nitrite)

### Step 2: Analyze the Decomposition of Each Compound
We will examine the thermal decomposition of each compound to see which one produces NO₂.

#### a. Sodium Nitrate (NaNO₃)
When heated, sodium nitrate decomposes as follows:
\[ \text{2 NaNO}_3 \rightarrow \text{2 NaNO}_2 + \text{O}_2 \]
- **Products**: Sodium nitrite (NaNO₂) and oxygen (O₂).
- **NO₂ is not produced**.

#### b. Lithium Nitrate (LiNO₃)
When lithium nitrate is heated, it decomposes as follows:
\[ 4 \text{LiNO}_3 \rightarrow \text{Li}_2\text{O} + 4 \text{NO}_2 + \text{O}_2 \]
- **Products**: Lithium oxide (Li₂O), nitrogen dioxide (NO₂), and oxygen (O₂).
- **NO₂ is produced**.

#### c. Ammonium Nitrate (NH₄NO₃)
When ammonium nitrate is heated, it decomposes as follows:
\[ \text{NH}_4\text{NO}_3 \rightarrow \text{N}_2\text{O} + \text{H}_2\text{O} \]
- **Products**: Nitrous oxide (N₂O) and water (H₂O).
- **NO₂ is not produced**.

#### d. Ammonium Nitrite (NH₄NO₂)
When ammonium nitrite is heated, it decomposes as follows:
\[ \text{NH}_4\text{NO}_2 \rightarrow \text{N}_2 + \text{H}_2\text{O} \]
- **Products**: Nitrogen gas (N₂) and water (H₂O).
- **NO₂ is not produced**.

### Step 3: Conclusion
From the analysis, only lithium nitrate (LiNO₃) produces nitrogen dioxide (NO₂) upon heating. Therefore, the answer to the question is:

**Answer: Lithium Nitrate (LiNO₃)**

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