Which of the following elements can give `NO_(2)` as a by product on reaction with conc. `HNO_(3)`?

Options

A. `C`
B. `Cu`
C. `Zn`
D. `Sn`

Explanation

To determine which elements can produce \( NO_2 \) as a by-product when reacting with concentrated \( HNO_3 \), we will analyze the reactions of each element provided in the options.

### Step-by-Step Solution:

1. **Identify the Elements:**
Let's denote the elements as A, B, C, and D. We will analyze each element's reaction with concentrated \( HNO_3 \).

2. **Reaction of Carbon (C):**
- When carbon reacts with concentrated \( HNO_3 \):
\[ C + 4HNO_3 \rightarrow CO_2 + 4NO_2 + 2H_2O \]
- By-products: \( NO_2 \) is produced. Thus, carbon can give \( NO_2 \).

3. **Reaction of Copper (Cu):**
- When copper reacts with concentrated \( HNO_3 \):
\[ Cu + 4HNO_3 \rightarrow Cu(NO_3)_2 + 2NO_2 + 2H_2O \]
- By-products: \( NO_2 \) is produced. Thus, copper can give \( NO_2 \).

4. **Reaction of Zinc (Zn):**
- When zinc reacts with concentrated \( HNO_3 \):
\[ Zn + 4HNO_3 \rightarrow Zn(NO_3)_2 + 2NO_2 + 2H_2O \]
- By-products: \( NO_2 \) is produced. Thus, zinc can give \( NO_2 \).

5. **Reaction of Tin (Sn):**
- When tin reacts with concentrated \( HNO_3 \):
\[ Sn + 4HNO_3 \rightarrow Sn(NO_3)_2 + 4NO_2 + 2H_2O \]
- By-products: \( NO_2 \) is produced. Thus, tin can give \( NO_2 \).

6. **Conclusion:**
All the elements (Carbon, Copper, Zinc, and Tin) can produce \( NO_2 \) as a by-product when reacted with concentrated \( HNO_3 \).

### Final Answer:
All options (A, B, C, D) can give \( NO_2 \) as a by-product on reaction with concentrated \( HNO_3 \).

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