Which of the following metal Fe, Zn, Pb, Ag and Pt do not give a
metal nitrate on treatment with concentrated `HNO_3`?

Options

A. Fe and Pt
B. Fe and Zn
C. Fe , Ag and Pt
D. Pb , Ag and Pt

Answer

To determine which of the metals (Fe, Zn, Pb, Ag, and Pt) do not give a metal nitrate when treated with concentrated HNO3, we can analyze the reactivity of each metal with concentrated nitric acid.

### Step-by-Step Solution:

1. **Understand the Reaction with Concentrated HNO3**:
- Concentrated nitric acid (HNO3) reacts with many metals to form metal nitrates and nitrogen oxides. However, some metals do not react in this manner.

2. **Analyze Each Metal**:
- **Zinc (Zn)**: When zinc reacts with concentrated HNO3, it forms zinc nitrate (Zn(NO3)2) and hydrogen gas. Therefore, zinc does give a metal nitrate.
- **Iron (Fe)**: Iron reacts with concentrated HNO3 but forms a protective oxide layer (FeO or Fe2O3) on its surface, which prevents further reaction. Thus, iron does not produce a metal nitrate.
- **Lead (Pb)**: Lead can react with concentrated HNO3 to form lead nitrate (Pb(NO3)2). Therefore, lead does give a metal nitrate.
- **Silver (Ag)**: Silver reacts with concentrated HNO3 to produce silver nitrate (AgNO3). Thus, silver does give a metal nitrate.
- **Platinum (Pt)**: Platinum is a noble metal and does not react with concentrated HNO3. It also forms a protective oxide layer, preventing the formation of a metal nitrate.

3. **Conclusion**:
- The metals that do not give a metal nitrate on treatment with concentrated HNO3 are **Iron (Fe)** and **Platinum (Pt)**.

### Final Answer:
**Fe and Pt do not give a metal nitrate on treatment with concentrated HNO3.**

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