A mole is a fundamental unit in chemistry used to measure the amount of a substance. It is one of the base units in the International System of Units (SI). The concept of the mole is crucial because it helps chemists understand the relationship between mass and number of particles, such as atoms, molecules, or ions.
Let’s analyze each statement to identify which one best describes a mole:
1. It is 12 units of a given substance.
- This statement is incorrect. A mole is not simply 12 units of anything.
2. It contains [tex]\(6.02 \times 10^{23}\)[/tex] grams of sodium chloride.
- This statement is misleading because a mole does not correspond to a specific mass of a given substance. Instead, a mole refers to a specific number of particles.
3. It is the mass of 12 carbon atoms.
- This statement is incorrect. The mass of 12 carbon atoms is a very small amount and does not define a mole. A mole represents a larger, standardized quantity.
4. It contains [tex]\(6.02 \times 10^{23}\)[/tex] particles of a given substance.
- This statement is correct. A mole is defined as the amount of substance that contains as many entities (atoms, molecules, ions, etc.) as there are in 12 grams of carbon-12. This number is known as Avogadro's number, which is [tex]\(6.02 \times 10^{23}\)[/tex] particles.
Given these analyses, the statement that best describes a mole is:
It contains [tex]\(6.02 \times 10^{23}\)[/tex] particles of a given substance.
So, the correct choice is:
4
