Which of the following is chalcogen ?

Options

A. O
B. S
C. Se
D. All

Explanation

To determine which of the given options is a chalcogen, we can follow these steps:

### Step 1: Understand the Definition of Chalcogens
Chalcogens are the elements found in Group 16 of the periodic table. This group includes elements that are known for forming ores and are essential for various biological and chemical processes.

**Hint:** Remember that chalcogens are specifically found in Group 16 of the periodic table.

### Step 2: Identify the Elements in Group 16
The elements in Group 16 (the chalcogens) include:
- Oxygen (O)
- Sulfur (S)
- Selenium (Se)
- Tellurium (Te)
- Polonium (Po)

**Hint:** List the elements in Group 16 to see which ones are considered chalcogens.

### Step 3: Analyze the Given Options
The options provided are:
1. Oxygen
2. Sulfur
3. Selenium
4. All of the above

Now, we need to check which of these options are indeed chalcogens.

**Hint:** Compare each option with the list of chalcogens you identified in Step 2.

### Step 4: Confirm Each Option
- **Oxygen**: Yes, it is a chalcogen.
- **Sulfur**: Yes, it is a chalcogen.
- **Selenium**: Yes, it is a chalcogen.
- **All of the above**: Since all the previous options are chalcogens, this option is also correct.

**Hint:** If all individual elements listed in the options are chalcogens, then the option stating "All of the above" must be correct.

### Step 5: Conclusion
Since all the elements listed (oxygen, sulfur, and selenium) are chalcogens, the correct answer is option 4: "All of the above."

**Final Answer:** All of the above are chalcogens.