When an iron nail gets rusted, iron oxide is formed

Options

A. without any change in the weight of the nail.
B. with increase in the weight of the nail
C. with decrease in the weight of the nail
D. without any change in colour or weight of the nail

Explanation

To solve the question regarding the rusting of an iron nail and the formation of iron oxide, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Rusting**: Rusting is a chemical process that occurs when iron reacts with oxygen in the presence of moisture (water). This process leads to the formation of iron oxide, commonly known as rust.

2. **Chemical Reaction**: The chemical equation for the rusting of iron can be represented as:
\[ 4Fe + 3O_2 + 6H_2O \rightarrow 4Fe(OH)_3 \]
Upon further dehydration, this can also be represented as:
\[ 4Fe(OH)_3 \rightarrow 2Fe_2O_3 \cdot 3H_2O \]
This shows that iron (Fe) combines with oxygen (O) and water (H2O) to form hydrated iron(III) oxide (rust).

3. **Weight Change**: When an iron nail rusts, it combines with oxygen and water, which means that the total mass of the nail increases. This is because the mass of the iron nail is being added to the mass of the oxygen and water that it reacts with.

4. **Options Analysis**:
- **Option A**: Without any change in weight of the nail - Incorrect, as the weight increases.
- **Option B**: Without increase in weight of the nail - Incorrect, as the weight does increase.
- **Option C**: With decrease in weight of the nail - Incorrect, as the weight does not decrease.
- **Option D**: Without any change in colour or weight of the nail - Incorrect, as both weight and appearance change.

5. **Correct Answer**: The correct option is **B**: with an increase in the weight of the nail due to the formation of rust.