Which of the following statements is incorrect?

Options

A. One gram atom of carbon contains avogadro's number of atoms.
B. One mole of oxygen gas contains avogadro's number of molecules.
C. One mole of hydrogen gas contains avogadro's number of atoms.
D. One mole of electrons stands for `6.02xx10^(23)` electrons.

Answer

To determine which of the statements is incorrect, we need to analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Understanding Moles and Avogadro's Number**:
- Avogadro's number (approximately \(6.02 \times 10^{23}\)) is the number of particles (atoms, molecules, etc.) in one mole of a substance.
- The number of moles can be calculated using the formula:
\[ \text{Number of moles} = \frac{\text{Given mass}}{\text{Molar mass}} \]

2. **Analyzing the First Statement**:
- The statement claims that "one gram of carbon contains Avogadro's number of carbon atoms."
- The molar mass of carbon (C) is 12 g/mol. Therefore, the number of moles in 1 gram of carbon is:
\[ \text{Number of moles} = \frac{1 \text{ g}}{12 \text{ g/mol}} = \frac{1}{12} \text{ moles} \]
- To find the number of carbon atoms, we multiply the number of moles by Avogadro's number:
\[ \text{Number of atoms} = \frac{1}{12} \times 6.02 \times 10^{23} \approx 5.02 \times 10^{22} \text{ atoms} \]
- This is not equal to Avogadro's number, hence this statement is incorrect.

3. **Analyzing the Second Statement**:
- The statement says "1 mole of oxygen gas (O2) contains Avogadro's number of O2 molecules."
- Since 1 mole of any substance contains Avogadro's number of particles, this statement is correct.

4. **Analyzing the Third Statement**:
- The statement claims "1 mole of hydrogen gas (H2) contains Avogadro's number of H2 molecules."
- Similar to the previous statement, this is also correct as 1 mole of H2 will contain \(6.02 \times 10^{23}\) molecules of H2.

5. **Analyzing the Fourth Statement**:
- The statement states "1 mole of electrons contains Avogadro's number of electrons."
- Again, this is correct because 1 mole of any particle (including electrons) contains \(6.02 \times 10^{23}\) of those particles.

### Conclusion:
The only incorrect statement is the first one, which claims that one gram of carbon contains Avogadro's number of carbon atoms.

### Final Answer:
**The incorrect statement is: "One gram of carbon contains Avogadro's number of carbon atoms."**

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