The correct option is 6.02214076 × 10^23.
Explanation
The Avogadro constant ($N_A$) is the fundamental physical constant that relates the amount of substance (measured in moles) to the number of constituent particles (such as atoms or molecules). In the 2019 redefinition of SI base units, the definition of the mole was decoupled from the mass of Carbon-12 and tied directly to a fixed numerical value of the Avogadro constant.Detailed Analysis:
- 6.02214076 × 10^23 is Correct: As per the current SI definition (effective May 20, 2019), the Avogadro constant is set to the exact fixed numerical value of $6.02214076 \times 10^{23}$ when expressed in the unit mol$^{-1}$. This value is exact and defines the magnitude of the mole.
- 6.0221367 × 10^23 is Incorrect: This value does not correspond to the current defined standard. It resembles older experimental measurements which had associated uncertainties.
- 6.023 × 10^23 is Incorrect: $6.023 \times 10^{23}$ is a traditional approximation often used for simplified calculations. It is not the precise value defined by the General Conference on Weights and Measures (CGPM).
- 6.62607015 × 10^23 is Incorrect: The significand $6.62607015$ belongs to the Planck constant ($h$), which has the exact value $6.62607015 \times 10^{-34}$ J s. It is unrelated to the Avogadro constant.
Key Takeaway:
The mole is currently defined by fixing the numerical value of the Avogadro constant to exactly $6.02214076 \times 10^{23}$, ensuring stability in scientific measurements independent of physical artifacts.