To determine which statement best describes a mole, let's analyze each given option carefully.
1. "It is 12 units of a given substance."
- This statement is incorrect. A mole is not defined as just 12 units of any substance. Instead, it is a much larger quantity, specifically related to a fundamental constant in chemistry.
2. "It contains [tex]$6.02 \times 10^{23}$[/tex] grams of sodium chloride."
- This statement is also incorrect. While [tex]$6.02 \times 10^{23}$[/tex] is Avogadro's number, it does not represent grams of a substance. Avogadro's number represents the number of particles (atoms, molecules, etc.) in one mole of a substance.
3. "It is the mass of 12 carbon atoms."
- This statement is incorrect as well. A mole is not defined by the mass of 12 carbon atoms. Instead, a mole of carbon atoms specifically contains [tex]$6.02 \times 10^{23}$[/tex] carbon atoms, not just 12.
4. "It contains [tex]$6.02 \times 10^{23}$[/tex] particles of a given substance."
- This statement is correct. A mole, by definition, contains [tex]$6.02 \times 10^{23}$[/tex] particles of a given substance. This number, known as Avogadro's number, is a fundamental constant used to describe the number of atoms, molecules, or ions in one mole of a substance.
Thus, the statement that best describes a mole is:
"It contains [tex]$6.02 \times 10^{23}$[/tex] particles of a given substance."
The correct answer is the fourth statement.
