Which process does not form `H_(2)` gas.

Options

A. `Zn+"ice cold "H_(2)O`
B. `Zn+H_(2)SO_(4)`
C. `Na+"ice cold "H_(2)O`
D. `Mg+"Hot"H_(2)O`

Answer

To determine which process does not form hydrogen gas, we will analyze each option provided in the question step by step.

### Step 1: Analyze the reaction of zinc with ice cold water.
- **Reaction**: Zinc + Ice Cold Water
- **Analysis**: Zinc is a less reactive metal and does not react with ice cold water. Since there is no reaction, hydrogen gas will not be produced.
- **Conclusion**: This process does not form hydrogen gas.

### Step 2: Analyze the reaction of zinc with sulfuric acid.
- **Reaction**: Zinc + Sulfuric Acid (H₂SO₄)
- **Analysis**: Zinc is more reactive than hydrogen and can displace hydrogen from sulfuric acid. The reaction will produce zinc sulfate and hydrogen gas.
- **Equation**: Zn + H₂SO₄ → ZnSO₄ + H₂↑
- **Conclusion**: This process does form hydrogen gas.

### Step 3: Analyze the reaction of sodium with ice cold water.
- **Reaction**: Sodium + Ice Cold Water
- **Analysis**: Sodium is a highly reactive alkali metal and reacts vigorously with ice cold water to produce sodium hydroxide and hydrogen gas.
- **Equation**: 2Na + 2H₂O → 2NaOH + H₂↑
- **Conclusion**: This process does form hydrogen gas.

### Step 4: Analyze the reaction of magnesium with hot water.
- **Reaction**: Magnesium + Hot Water
- **Analysis**: Magnesium is less reactive than sodium but can react with hot water to produce magnesium hydroxide and hydrogen gas.
- **Equation**: Mg + 2H₂O (hot) → Mg(OH)₂ + H₂↑
- **Conclusion**: This process does form hydrogen gas.

### Final Conclusion:
Based on the analysis of each option, the process that does not form hydrogen gas is the reaction of zinc with ice cold water.

### Answer:
Zinc reacting with ice cold water does not form hydrogen gas.

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