Year 8 Science — Solutes, solvents and solutions

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

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

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

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

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

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

4.Gases behave the other way round from solids. What happens to the solubility of a gas in water as the water warms up?

• a) It decreases
• b) It stays the same
• c) It increases up to 50 °C and decreases after that
• d) It increases

5.Why does dissolved oxygen matter in a pond?

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

6.The greatest amount of solute a fixed quantity of solvent will dissolve at a particular temperature has a one-word name. What is it?

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

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

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