Which of the following is a covalent oxide?

Options

A. BeO
B. CaO
C. SrO
D. BaO

Answer

To determine which of the following is a covalent oxide, we need to analyze the properties of the oxides formed by the elements in the second group of the periodic table (alkaline earth metals). The elements in this group include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).

### Step-by-Step Solution:

1. **Identify the Elements**: The elements in the second group (alkaline earth metals) are:
- Beryllium (Be)
- Magnesium (Mg)
- Calcium (Ca)
- Strontium (Sr)
- Barium (Ba)

2. **Understand the Oxides**: Each of these elements forms oxides when they react with oxygen. The general formula for the oxides of alkaline earth metals is \( M_xO_y \), where \( M \) is the metal.

3. **Electropositivity Trend**: As we move down the group from beryllium to barium, the electropositivity of the metals increases. This means that the ability of the metal to lose electrons and form positive ions increases.

4. **Covalent Character**: The covalent character of an oxide increases with increasing electropositivity. Beryllium, being the least electropositive in the group, has a higher tendency to form covalent bonds compared to the other alkaline earth metals.

5. **Identify the Covalent Oxide**: Among the oxides of these metals:
- Beryllium oxide (BeO) is known to exhibit covalent character due to the small size and high charge density of the Be²⁺ ion.
- The other oxides, such as magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO), are predominantly ionic.

6. **Conclusion**: Therefore, the covalent oxide among the options provided is **Beryllium oxide (BeO)**.

### Final Answer:
**Beryllium oxide (BeO) is a covalent oxide.**