The mole is based on the mass of 12 grams of ____.

• A. carbon-12
• B. nitrogen-14
• C. hydrogen-1
• D. oxygen-16

Answer: (A)

Verified step by step guidance

1. Understand that the mole is a fundamental unit in chemistry used to count particles, such as atoms or molecules.
2. Recall that the mole is defined based on a specific isotope of an element, which serves as the standard reference.
3. Recognize that the mole is defined as the amount of substance containing as many entities as there are atoms in exactly 12 grams of carbon-12.
4. Identify that carbon-12 is the isotope used to define the mole, not nitrogen-14, hydrogen-1, or oxygen-16.
5. Conclude that the mole is based on the mass of 12 grams of carbon-12.