Understanding how to approach exam questions helps to boost exam performance. Question types will include multiple choice, structured, mathematical and practical questions.

You will complete 21 required practical activities if you are studying GCSE combined science: Synergy. You could be asked questions about the apparatus, methods, safety precautions, results, analysis and evaluation of these experiments.

There will be a number of different types of practical based questions. Some will be on the set required practicals, some will cover the working scientifically terms and some will be on other science practicals which you might have done in class. Use all the information given in the question particularly any diagrams to help you understand what the question is about.

*This page contains AQA material which is reproduced by permission of AQA.*

- Question
A student reacted four metals with water and with dilute acid to work out the order of reactivity of the metals.

The table shows some of the observations.

Metal Reaction with water Reaction with dilute acid Calcium Bubbles of gas **X**Copper **Y**No bubbles of gas Magnesium Few bubbles of gas Bubbles of gas Zinc No bubbles of gas Bubbles of gas Write down the observations for

**X**and**Y**.**[2 marks]****X**bubbles of gas [1].**Y**no bubbles of gas [1].

- Question
A student investigates how the concentration of an acid affects the rate of a reaction.

This is the method used.

- Put a 3 cm piece of magnesium ribbon into a conical flask.
- Add 50 cm
^{3}of 0.5 mol/dm^{3}hydrochloric acid into the flask. - Collect and measure the volume of gas produced at 10 second intervals.
- Repeat with different concentrations of hydrochloric acid using the same length of magnesium ribbon and volume of acid.

The student's results are shown in the graph below: .

How do the results show that increasing the concentration of acid increases the rate of reaction?

You

**must**use data from the graph in your answer.**[2 marks]**As the concentration increases:

- the relationship is identified from the graph [1]
- example: the same volume of gas is collected in a shorter time or more gas is collected in the same time or reaction reaches completion in a shorter time

- reference to relevant data to evidence relationship [1]
- example: 20 cm
^{3}collected in 10 seconds at 0.5 mol/dm^{3}in 6.5 s at 1.0 mol/dm^{3}and in 4 seconds at 2.0 mol/dm^{3} - example: at 10 seconds volume collected is 20 cm
^{3}with 1.0 mol/dm^{3}, 30 cm^{3}with 1.0 mol/dm^{3}, 50 cm^{3}with 2.0 mol/dm^{3} - example: total volume collected reaches maximum of 100 cm
^{3}in 20 seconds at 2.0 mol/dm^{3}but takes twice as long at 1.0 cm^{3}and at 0.5 mol/dm^{3}

- example: 20 cm

- the relationship is identified from the graph [1]

- Question
A student is investigating some electrical components.

Describe how the student could set up a circuit to find the resistance of a lamp.

You should include a circuit diagram in your answer.

**[4 marks]**If ammeter is connected in series and voltmeter in parallel [2].

Measure the potential difference across the lamp at known current [1].

Calculate resistance from measured values using [1].

- Question
A student is investigating some electrical components.

The student is given an electrical component in a sealed box.

She has to find out what the electrical component is by experiment.

Her results are shown in the graph below.

Explain how the student could know that the electrical component in the sealed box is not an ohmic conductor.

**[2 marks]**For ohmic conductors the current is directly proportional to the potential difference applied across it [1].

This graph is curved so it is not an ohmic conductor [1].