Step 1: Comprehend Redox Reactions
A redox reaction encompasses both reduction and oxidation. Oxidation signifies electron loss, while reduction signifies electron gain.
Step 2: Determine Oxidation and Reduction in Each Option
Analysis of each option:
- Option (1): \( \text{H}_2 \) and \( \text{Cl}_2 \) react. Hydrogen is oxidized (electron loss), and chlorine is reduced (electron gain). This is a redox reaction.
- Option (2): \( \text{NaCl} + \text{AgNO}_3 \) yields \( \text{NaNO}_3 + \text{AgCl} \). This is a double displacement reaction, not a redox reaction.
- Option (3): Ethanol combustion is a redox reaction.
- Option (4): The synthesis of water from hydrogen and oxygen is a redox reaction.
Answer: Option (1) depicts a redox reaction with hydrogen oxidation and chlorine reduction. Thus, option (1) is the correct choice.