Lesson 7 Atoms and Molecules

Q1. How many particles are present in one mole?

6.022 × 10^23 6.022 × 10^20 3.011 × 10^23 1.000 × 10^23

Q2. The mole is the SI unit for the amount of:

Amount of substance Mass Time Temperature

Q3. An atom has 11 protons and 12 neutrons. What is its mass number?

11 12 23 1

Q4. How do the total numbers of atoms compare in 2 mol H₂ and 1 mol O₂?

Double in H₂ Equal Double in O₂ Zero

Q5. What type of molecule is P₄?

Tetra-atomic molecule Diatomic molecule Triatomic molecule Monoatomic

Q6. How is molecular mass calculated?

By adding relative atomic masses of all constituent atoms By adding only atomic numbers By adding only neutron numbers By dividing by number of moles

Q7. The relative atomic mass of an element is compared with:

1/12 of the mass of a carbon-12 atom The entire mass of a hydrogen atom The entire mass of an oxygen-16 atom The mass of one electron

Q8. What is the molar mass of Ca₃(PO₄)₂? (Ca=40,P=31,O=16)

310 g mol⁻¹ 308 g mol⁻¹ 286 g mol⁻¹ 300 g mol⁻¹

Q9. What does an empirical formula show?

Simplest whole-number ratio of atoms Always the actual total atoms in a molecule Number of electrons Only number of neutrons

Q10. How many helium atoms are in 2 mol of helium?

1.2044 × 10^24 6.022 × 10^23 3.011 × 10^23 2