Which one of the following statements is incorrect?

Options

A. One gram atom of carbon-12 contains Avogadro's number of atoms.
B. One mole of oxygen gas contains Avogadro's number of molecules.
C. One mole hydrogen gas contains Avogadro's number of atoms.
D. One mole of electron stands for '6.02 x 10^23' electrons.

Explanation

To determine which statement is incorrect among the provided options, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Analyze Statement A:**
- Statement: "1 gram atom of carbon-12 contains Avogadro number of atoms."
- Explanation: 1 gram atom of carbon-12 is equivalent to 1 mole of carbon-12. According to Avogadro's Law, 1 mole of any substance contains Avogadro's number of particles (atoms, molecules, etc.), which is approximately \(6.02 \times 10^{23}\). Therefore, this statement is **correct**.

2. **Analyze Statement B:**
- Statement: "1 mole of oxygen gas contains Avogadro's number of molecules."
- Explanation: 1 mole of oxygen gas (O₂) indeed contains Avogadro's number of molecules. Since O₂ is a diatomic molecule, 1 mole of O₂ will have \(6.02 \times 10^{23}\) O₂ molecules. Thus, this statement is **correct**.

3. **Analyze Statement C:**
- Statement: "1 mole hydrogen gas contains Avogadro's number of atoms."
- Explanation: 1 mole of hydrogen gas (H₂) contains Avogadro's number of molecules, not atoms. Each H₂ molecule consists of 2 hydrogen atoms. Therefore, 1 mole of H₂ contains \(6.02 \times 10^{23}\) molecules of H₂, which corresponds to \(2 \times 6.02 \times 10^{23}\) hydrogen atoms. Thus, this statement is **incorrect**.

4. **Analyze Statement D:**
- Statement: "1 mole of electrons stands for \(6.02 \times 10^{23}\) electrons."
- Explanation: This statement is correct as well. 1 mole of any elementary charge, including electrons, contains Avogadro's number of particles, which is \(6.02 \times 10^{23}\). Therefore, this statement is **correct**.

### Conclusion:
The incorrect statement is **C**: "1 mole hydrogen gas contains Avogadro's number of atoms."

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