Only one element of …….from hydride.

Options

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

Explanation

To solve the question regarding which group contains only one element that forms a hydride, we can follow these steps:

### Step 1: Identify the Groups
We are given four groups to analyze: Group 6, Group 7, Group 8, and Group 9.

### Step 2: Analyze Each Group
- **Group 6**: This group includes Chromium (Cr).
- **Group 7**: This group includes Manganese (Mn).
- **Group 8**: This group includes Iron (Fe).
- **Group 9**: This group includes Cobalt (Co).

### Step 3: Determine Hydride Formation
- **Group 6**: Chromium is known to form a hydride, specifically Chromium Hydride (CrH).
- **Group 7, 8, and 9**: Elements in these groups (Mn, Fe, Co) do not form hydrides. This is referred to as the hydride gap.

### Step 4: Conclusion
From the analysis, we find that only Chromium from Group 6 forms a hydride. Therefore, the answer to the question is Group 6.

### Final Answer:
**Group 6** is the only group that contains one element (Chromium) that forms a hydride.

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