An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be:

Options

A. calcium
B. carbon
C. silicon
D. iron

Explanation

To determine which element is likely to react with oxygen to form a compound with a high melting point that is also soluble in water, we can analyze the options provided: calcium, carbon, silicon, and iron.

### Step-by-Step Solution:

1. **Identify the Elements**: The elements given are:
- A: Calcium (Ca)
- B: Carbon (C)
- C: Silicon (Si)
- D: Iron (Fe)

2. **Consider the Reaction with Oxygen**:
- When **Calcium** reacts with oxygen, it forms **Calcium Oxide (CaO)**.
- When **Carbon** reacts with oxygen, it forms **Carbon Dioxide (CO2)**.
- When **Silicon** reacts with oxygen, it forms **Silicon Dioxide (SiO2)**.
- When **Iron** reacts with oxygen, it forms various oxides like **Iron(III) Oxide (Fe2O3)**.

3. **Evaluate the Melting Points**:
- **Calcium Oxide (CaO)** has a high melting point of about **2572°C**.
- **Carbon Dioxide (CO2)** is a gas at room temperature and does not have a melting point in the same way as solids do.
- **Silicon Dioxide (SiO2)** has a high melting point but is insoluble in water.
- **Iron Oxides** have varying melting points but are not known for high solubility in water.

4. **Check Solubility in Water**:
- **Calcium Oxide (CaO)** is soluble in water, forming **Calcium Hydroxide (Ca(OH)2)**.
- **Carbon Dioxide (CO2)** is soluble in water but does not form a solid compound with a high melting point.
- **Silicon Dioxide (SiO2)** is insoluble in water.
- **Iron Oxides** have limited solubility in water.

5. **Conclusion**: Based on the analysis, the element that reacts with oxygen to form a compound with a high melting point and is also soluble in water is **Calcium (Ca)**.

### Final Answer:
The element is likely to be **Calcium (A)**.

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