Question

practice: what is a mole?
which of the following is not true?
the mole is a word for a number just like \dozen = 12\ or \decade = 10 years\
the mole is a unit of measurement
the mole is equal to avogadro’s number, $6.02 \times 10^{23}$
the mole is used to count atoms in chemistry
there are $2.06 \times 10^{20}$ atoms in a mole

Explanation:

1. Analyze each option:

• The mole is a counting unit like dozen (12) or decade (10 years) – this is true as mole represents a specific number of entities.
• The mole is a unit of measurement (for amount of substance) – this is true.
• The mole is equal to Avogadro’s number ($6.02\times10^{23}$) – this is true as 1 mole of a substance contains $6.02\times10^{23}$ entities.
• The mole is used to count atoms in chemistry – this is true as it helps in quantifying atoms, molecules, etc.
• The statement "There are $2.06\times10^{20}$ atoms in a mole" is false because 1 mole contains $6.02\times10^{23}$ entities (atoms, molecules, etc.), not $2.06\times10^{20}$.

Answer:

The option that is NOT true is: There are $2.06\times10^{20}$ atoms in a mole