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Key Stage 3 Science Book 1 Assessments

Mixing, Dissolving and Separating (Blue level) Answers

1. Hamid is going to heat sodium chloride and water in a beaker. How can he carry out his experiment as safely as possible? [4 marks]

(the answer should contain four of the following)

1) Use a tripod and gauze to put the beaker on

2) Use a heat proof mat

3) Wear goggles

4) Leave the beaker to cool before touching it

5) Heat it gently with a Bunsen burner

6) Do not eat or drink while carrying out the procedure

7) Any other suitable response relating to safety

Difficulty level: moderate

Skill level: knowledge

2. Anne has set up an experiment to grow a crystal. It looks like this:

A week later the crystal is larger. Which of these is a correct explanation as to why? [1 mark]

d)

Difficulty level: easy

Skill level: application

3. Which of the following is not a mixture? [1 mark]

a)



© HarperCollinsPublishers 2014


4. Which of these techniques is not involved in obtaining salt from rock salt? [1 mark]

d)



5. Which two processes are involved in distillation? [2 marks]

d), e)



6. Match the description to the picture. [3 marks]

Two elements

An element

Mixture of an element and a compound

A compound

Mixture of two compounds



7. Why is water not the only solvent we use to remove stains? [2 marks]

(the answer should contain the following)

1) Some materials are insoluble in water

2) But they are soluble in other solvents





8. After a hit and run accident involving a car, the police collected some samples of paint from the crime scene. They have a suspect. How can the paint be tested to help the police confirm if they have the correct suspect or not? [2 marks]


1) Use chromatography to separate the dyes

2) Use a sample from the crime scene and a sample from the suspect’s car to see if they match



9. What is produced when copper reacts with oxygen? [1 mark]

d)



10. How would you separate water from a solution of copper sulfate? [2 marks]


1) Heat the solution in a flask to evaporate the water

2) Distil the vapour/use a Liebig condenser to condense the water



11. Leroy used chromatography to investigate the food colourings used in some of his favourite sweets. Here’s a black and white diagram of the chromatogram, which shows his results.

Which two sweets probably contained the same mixture of food colourings? [1 mark]

d)


Skill level: evaluation



12. Leroy used chromatography to investigate the food colourings used in some of his favourite sweets. Here’s a black and white diagram of the chromatogram, which shows his results.

What is the best conclusion that Leroy could make about sweets C and D? [1 mark]

d)



13. Look carefully at this table of results.

How can the results table be improved? Select three possibilities. [3 marks]

a), c), e)

Difficulty level: difficult


14. Emma is making jelly. In order to make it dissolve quickly, should Emma put the block of jelly in whole, or break it into cubes? Explain your answer. [2 marks]


1) She should break it into cubes

2) There is greater surface area for the solvent (water) to reach





15. Ben and Lucy investigated how much copper sulfate would dissolve in 100 cm3 of water at different temperatures. This is a graph of their results.

What do their results tell them? [2 marks]


1) The hotter the water the more copper sulfate dissolves



16. Keisha has noticed that the tap water in the laboratory leaves a white substance around the tap when it dries up. Why has this happened? [2 marks]


1) The water has evaporated

2) Leaving behind limescale/calcium salts/substances that were dissolved in it




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