Which of the following contains the greatest number of atoms ?

Options

A. 1 g of O
B. 1 g of `O_(2)`
C. 1g of `O_(3)`
D. 1 g `F_(2)`

Answer

To determine which of the given options contains the greatest number of atoms, we will calculate the number of moles and subsequently the number of atoms for each substance. The options are:

1. 1 gram of O (oxygen)
2. 1 gram of O2 (dioxygen)
3. 1 gram of O3 (ozone)
4. 1 gram of F2 (fluorine)

### Step 1: Calculate the number of moles for each substance

1. **For O (oxygen)**:
- Molar mass of O = 16 g/mol
- Number of moles = mass / molar mass = 1 g / 16 g/mol = 1/16 mol

2. **For O2 (dioxygen)**:
- Molar mass of O2 = 32 g/mol
- Number of moles = mass / molar mass = 1 g / 32 g/mol = 1/32 mol

3. **For O3 (ozone)**:
- Molar mass of O3 = 48 g/mol
- Number of moles = mass / molar mass = 1 g / 48 g/mol = 1/48 mol

4. **For F2 (fluorine)**:
- Molar mass of F2 = 38 g/mol
- Number of moles = mass / molar mass = 1 g / 38 g/mol = 1/38 mol

### Step 2: Calculate the number of molecules for each substance

Using Avogadro's number (Na = 6.022 x 10^23 molecules/mol):

1. **For O**:
- Number of molecules = (1/16 mol) × Na = Na / 16

2. **For O2**:
- Number of molecules = (1/32 mol) × Na = Na / 32

3. **For O3**:
- Number of molecules = (1/48 mol) × Na = Na / 48

4. **For F2**:
- Number of molecules = (1/38 mol) × Na = Na / 38

### Step 3: Calculate the number of atoms for each substance

1. **For O (oxygen)**:
- Number of atoms = Number of molecules × atomicity = (Na / 16) × 1 = Na / 16

2. **For O2 (dioxygen)**:
- Number of atoms = Number of molecules × atomicity = (Na / 32) × 2 = Na / 16

3. **For O3 (ozone)**:
- Number of atoms = Number of molecules × atomicity = (Na / 48) × 3 = Na / 16

4. **For F2 (fluorine)**:
- Number of atoms = Number of molecules × atomicity = (Na / 38) × 2 = Na / 19

### Step 4: Compare the number of atoms

- O: Na / 16
- O2: Na / 16
- O3: Na / 16
- F2: Na / 19

### Conclusion

The number of atoms in 1 gram of O, O2, and O3 is the same (Na / 16), while the number of atoms in 1 gram of F2 is Na / 19. Therefore, the substances that contain the greatest number of atoms are:

**Answer: A (O), B (O2), and C (O3)**