Only one element of __________ forms hydrode.

Options

A. group 6
B. group 7
C. group 8
D. group 9

Explanation

To solve the question "Only one element of __________ forms hydride," we need to identify which element from the periodic table forms hydrides.

### Step-by-Step Solution:

1. **Understanding Hydrides**:
- A hydride is a compound formed between hydrogen and another element. It is important to know which elements can form hydrides.

2. **Identifying the Group**:
- The question specifies that we are looking for an element from a specific group in the periodic table. In this case, we focus on Group 6 elements.

3. **Listing Group 6 Elements**:
- The elements in Group 6 of the periodic table are Oxygen (O), Sulfur (S), Selenium (Se), Tellurium (Te), and Chromium (Cr).

4. **Analyzing Each Element**:
- **Oxygen**: Forms water (H2O) and hydrogen peroxide (H2O2) but is not typically referred to as a hydride in this context.
- **Sulfur**: Forms hydrogen sulfide (H2S), which is a hydride.
- **Selenium**: Forms hydrogen selenide (H2Se), which is also a hydride.
- **Tellurium**: Forms hydrogen telluride (H2Te), another hydride.
- **Chromium**: Forms chromium hydride (CrH), which is less common but is indeed a hydride.

5. **Conclusion**:
- Among the Group 6 elements, while several can form hydrides, the question specifically states that only one element forms hydride in a significant context. This is typically understood to refer to Chromium (Cr) in certain contexts, especially in relation to its unique properties and lower affinity for hydrogen compared to others in the group.

6. **Final Answer**:
- The answer to the fill-in-the-blank question is "Group 6" or "Chromium".