← Back to the activity

Class 8 Science — Solutes, solvents and solutions

Name the solute and the solvent in a solution, tell a saturated solution from an unsaturated one, and say how temperature changes what will dissolve.

Name: ________________________

  1. 1.In a glass of salt water, what is the water called? Give the one word.

  2. 2.Alcohol and water are mixed, with rather more water than alcohol. Which is the solute?

    • a) The alcohol, because it is the one present in the smaller amount
    • b) Both, because liquids mixed together are both solutes
    • c) Neither, because two liquids cannot form a solution
    • d) The water, because it is a liquid

  3. 3.Which is the more concentrated solution: 2 spoons of salt in 100 mL of water, or 4 spoons in 50 mL?

    • a) 2 spoons in 100 mL, since there is more water to spread through
    • b) Neither, because concentration applies to gases rather than solids
    • c) They are equally concentrated, since both use salt and water
    • d) 4 spoons in 50 mL, since more solute sits in less solution

  4. 4.For most solids dissolving in a liquid, what does raising the temperature do to the solubility?

    • a) It increases it
    • b) It increases it for salts and decreases it for sugars
    • c) It leaves it unchanged
    • d) It decreases it

  5. 5.Each sip of a homemade oral rehydration solution tastes the same as the last. Why?

    • a) The sugar settles at the bottom and the salt stays at the top
    • b) The water dilutes both of them until neither can be tasted
    • c) The sugar and salt are evenly distributed through the whole of the water
    • d) The sugar and salt cancel out each other's taste

  6. 6.Why does dissolved oxygen matter in a pond?

    • a) It keeps the water from freezing in winter
    • b) It is what sustains the plants, fish and other organisms living in the water
    • c) It stops other gases from dissolving in the water
    • d) It makes the water taste better

  7. 7.Spoons of salt are stirred into a glass of water one after another. Put the four stages back into order.

    • The undissolved salt settles at the bottom
    • The first spoon of salt dissolves completely
    • More spoons go in and still dissolve
    • A spoon is added that does not fully dissolve

  8. 8.Which statement about a saturated solution is the right one?

    • a) No more solute can be dissolved into it at that temperature
    • b) It forms at high temperatures and nowhere else
    • c) It can still dissolve more solute at that temperature
    • d) It has dissolved less solute than an unsaturated solution

Answer key — Class 8 Science — Solutes, solvents and solutions

  1. 1. solvent
  2. 2. a) The alcohol, because it is the one present in the smaller amount
  3. 3. d) 4 spoons in 50 mL, since more solute sits in less solution
  4. 4. a) It increases it
  5. 5. c) The sugar and salt are evenly distributed through the whole of the water
  6. 6. b) It is what sustains the plants, fish and other organisms living in the water
  7. 7. 1. The first spoon of salt dissolves completely 2. More spoons go in and still dissolve 3. A spoon is added that does not fully dissolve 4. The undissolved salt settles at the bottom
  8. 8. a) No more solute can be dissolved into it at that temperature