Topic 1.1 Moles and Molar Mass

What is Avogadro's number?

What does Avogadro's number represent?

• The number of atoms in a molecule

• The number of particles in one mole of a substance

• The mass of one mole of a substance

• The volume of one mole of a gas

How is the mass of an individual atom or molecule expressed?

• In grams

• In atomic mass units (amu)

• In liters

• In moles

Why is it useful to express the mass of an atom in atomic mass units (amu)?

• It simplifies calculations

• It is numerically equal to the molar mass in grams

• It is a smaller unit than grams

• It is a larger unit than grams

What is the relationship between the molar mass of a substance and its atomic mass in amu?

• They are inversely proportional

• They are numerically equal

• The molar mass is always greater

• The atomic mass is always greater

• 0.5 moles

• 2 moles

• 1 mole

• 3 moles

If a substance has a molar mass of 18 g/mol, what is the mass of one molecule in amu?

• 18 amu

• 9 amu

• 36 amu

• 1 amu

Which of the following statements is true about the mole concept?

• It allows direct counting of particles

• It connects the mass of a substance to the number of particles

• It is only applicable to gases

• It is not related to Avogadro's number

A sample contains 3 moles of a substance. How many particles does it contain?

Explain why it is not possible to count particles directly in laboratory work.

• Particles are too small to be seen

• There are too many particles

• Both A and B

• Neither A nor B