States of Matter, Gas Laws, Mixtures and the Mole

Attempt the quiz above first, then review every question with its correct answer and a short explanation below.

1. Q1.The fourth state of matter is:

   • A.liquid crystal
   • B.colloid
   • C.plasma✓ Correct Answer
   • D.alloy

   Explanation: Plasma is an ionised gas, as found in the Sun and stars.

2. Q2.Dry ice is the solid form of:

   • A.water
   • B.carbon dioxide✓ Correct Answer
   • C.nitrogen
   • D.ammonia

   Explanation: It sublimes directly into gas.

3. Q3.The change of a solid directly into a gas is called:

   • A.condensation
   • B.fusion
   • C.freezing
   • D.sublimation✓ Correct Answer

   Explanation: Camphor and naphthalene sublime.

4. Q4.Boyle's law relates the pressure and volume of a gas at constant:

   • A.temperature✓ Correct Answer
   • B.mass of container
   • C.colour
   • D.density of air

   Explanation: P × V is constant: pressure is inversely proportional to volume.

5. Q5.The change of ice into water is called:

   • A.sublimation
   • B.evaporation
   • C.melting (fusion)✓ Correct Answer
   • D.condensation

   Explanation: It occurs at 0 °C at normal pressure.

6. Q6.Which state of matter has both a definite shape and a definite volume?

   • A.solid✓ Correct Answer
   • B.liquid
   • C.gas
   • D.plasma

   Explanation: Particles in a solid are tightly packed.

7. Q7.Charles's law states that at constant pressure the volume of a gas is proportional to its:

   • A.mass of the container
   • B.absolute temperature✓ Correct Answer
   • C.pressure
   • D.colour

   Explanation: V / T is constant, with T in kelvin.

8. Q8.Avogadro's number is approximately:

   • A.6.022 × 10^23✓ Correct Answer
   • B.6.022 × 10^-23
   • C.3 × 10^8
   • D.9.8 × 10^23

   Explanation: It is the number of particles in one mole.

9. Q9.At STP, one mole of any ideal gas occupies about:

   • A.22.4 litres✓ Correct Answer
   • B.2.24 litres
   • C.1 litre
   • D.224 litres

   Explanation: This is the molar volume at standard temperature and pressure.

10. Q10.Evaporation causes:

    • A.heating
    • B.cooling✓ Correct Answer
    • C.no temperature change
    • D.freezing of the surroundings

    Explanation: The fastest molecules leave, lowering the average energy.

11. Q11.Which of the following is a mixture?

    • A.water
    • B.carbon dioxide
    • C.air✓ Correct Answer
    • D.sodium chloride

    Explanation: Air is a mixture of nitrogen, oxygen and other gases.

12. Q12.Water is classified as a:

    • A.element
    • B.mixture
    • C.compound✓ Correct Answer
    • D.alloy

    Explanation: It is made of hydrogen and oxygen in a fixed ratio.

13. Q13.Brass is an alloy of:

    • A.copper and tin
    • B.copper and zinc✓ Correct Answer
    • C.iron and carbon
    • D.lead and tin

    Explanation: Brass is made of copper and zinc in varying proportions.

14. Q14.Diffusion is fastest in:

    • A.solids
    • B.gases✓ Correct Answer
    • C.liquids
    • D.metals

    Explanation: Gas particles move freely with large gaps.

15. Q15.Salt can be obtained from sea water by:

    • A.filtration
    • B.magnetic separation
    • C.sublimation
    • D.evaporation✓ Correct Answer

    Explanation: Water evaporates in salt pans leaving crystals.

16. Q16.The law of conservation of mass was given by:

    • A.John Dalton
    • B.Joseph Proust
    • C.Antoine Lavoisier✓ Correct Answer
    • D.Robert Boyle

    Explanation: Mass is neither created nor destroyed in a chemical reaction.

17. Q17.The law of constant proportions was given by:

    • A.Antoine Lavoisier
    • B.Amedeo Avogadro
    • C.Dmitri Mendeleev
    • D.Joseph Proust✓ Correct Answer

    Explanation: A pure compound always contains the same elements in the same mass ratio.

18. Q18.The fifth state of matter is the:

    • A.plasma
    • B.liquid crystal
    • C.glass
    • D.Bose-Einstein condensate✓ Correct Answer

    Explanation: It forms near absolute zero.

19. Q19.The law of multiple proportions was proposed by:

    • A.Joseph Proust
    • B.Antoine Lavoisier
    • C.Robert Millikan
    • D.John Dalton✓ Correct Answer

    Explanation: It is illustrated by CO and CO2.

20. Q20.The mass of one mole of water is about:

    • A.18 g✓ Correct Answer
    • B.16 g
    • C.2 g
    • D.100 g

    Explanation: H2O = 2 × 1 + 16 = 18.