Question

which of the following is not true?

the mole is equal to avogadro’s number, $6.02 \times 10^{23}$

the mole is used to count atoms in chemistry

the mole is a word for a number just like \dozen = 12\ or \decade = 10 years\

there are $2.06 \times 10^{28}$ atoms in a mole

the mole is a unit of measurement

Explanation:

1. Recall the definition of a mole: A mole is defined as the amount of substance containing Avogadro's number ($6.02\times10^{23}$) of particles (atoms, molecules, ions, etc.).
2. Analyze each option:

• Option 1: The mole is equal to Avogadro’s number, $6.02\times 10^{23}$: This is correct. A mole of a substance contains $6.02\times10^{23}$ particles.
• Option 2: The mole is used to count atoms in chemistry: This is correct. The mole is a fundamental unit in chemistry for counting atoms, molecules, etc.
• Option 3: The mole is a word for a number just like "dozen = 12" or "decade = 10 years": This is correct. Similar to how a dozen represents 12 items, a mole represents $6.02\times10^{23}$ particles.
• Option 4: There are $2.06\times 10^{28}$ atoms in a mole: This is incorrect. A mole contains $6.02\times10^{23}$ particles, not $2.06\times 10^{28}$.
• Option 5: The mole is a unit of measurement: This is correct. The mole is the SI unit for the amount of substance.

Answer:

There are $2.06\times 10^{28}$ atoms in a mole