When a piece of sodium metal is dropped in water, hydrogen gas evolved because

Options

A. sodium is reduced and acts as an oxidising agent
B. water is oxidised and act as a reducing agent
C. sodium loses electrons and is oxidised while water is reduced
D. water loses electrons and is oxidised to hydrogen.

Explanation

To solve the question, "When a piece of sodium metal is dropped in water, hydrogen gas evolved because," we can follow these steps:

### Step 1: Identify the Reaction
When sodium (Na) is added to water (H2O), a chemical reaction occurs. The balanced equation for this reaction is:
\[ \text{2 Na} + \text{2 H}_2\text{O} \rightarrow \text{2 NaOH} + \text{H}_2 \uparrow \]

### Step 2: Understand the Oxidation and Reduction Process
In this reaction:
- Sodium (Na) is a metal that has one electron in its outermost shell (3s1). When it reacts with water, it loses this electron and gets oxidized to sodium ions (Na⁺).
- Water (H2O) contains hydrogen ions (H⁺). The H⁺ ions gain the electrons lost by sodium and are reduced to form hydrogen gas (H2).

### Step 3: Write the Half-Reactions
1. **Oxidation half-reaction** (for sodium):
\[ \text{Na} \rightarrow \text{Na}^+ + e^- \]

2. **Reduction half-reaction** (for hydrogen):
\[ \text{2 H}^+ + 2 e^- \rightarrow \text{H}_2 \]

### Step 4: Combine the Half-Reactions
Combining the half-reactions, we see that two sodium atoms will lose two electrons, which will be gained by two hydrogen ions:
\[ \text{2 Na} + \text{2 H}^+ \rightarrow \text{2 Na}^+ + \text{H}_2 \]

### Step 5: Conclusion
From the above steps, we conclude that:
- Sodium is oxidized (loses electrons) and acts as a reducing agent.
- Water is reduced (gains electrons) and acts as an oxidizing agent.
- The hydrogen gas (H2) is released as a product of this reaction.

Thus, the correct answer to the question is that hydrogen gas is evolved because sodium is oxidized and water is reduced.