Module 1

Question 1

What is an independent variable (2)

Answer 1

• variable that is changed in an experiment
• done to test its effects on the dependent variable

Question 2

What is a dependent variable ? (2)

Answer 2

• variable that is measured in an experiment
• this variable is affected by the independent variable

Question 3

What are controlled variables (2) ?

Answer 3

• factors that are kept constant during an experiment
• these ensure that any changes in the dependent variable are due to the independent variable only

Question 4

What is the mean of a data set ?

Answer 4

The mean is a measure of average.

• This is the sum of all values divided by the number of values in the data set

Question 5

What are qualitative observations? (2)

Answer 5

• Qualitative observations are observations that deal with descriptions.
• For example, this would include colours

Question 6

Quantitative observations

Answer 6

numerical values

Question 7

What is accuracy ?(2)

Answer 7

• Accuracy describes how close a reading is to the true value.
• A value is considered accurate if it is close to the true result

Question 8

How do you interpret volumes ?

Answer 8

• When reading volume from a measuring cylinder or syringe, take the measurement from where the meniscus is.

Question 9

How do you reduce random errors in measurements? (3)

Answer 9

• To reduce random errors, take multiple measurements and calculate an average.
• Use more precise instruments.
• Increase sample size

Question 10

What is the uncertainty in a measurement? (2)

Answer 10

• Uncertainty is the range within which the true value is expected to lie.
• This is given by the precision of the instrument used and the repeatability of the measurements

Question 11

How do you calculate the percentage uncertainty of a measurement ? (1)

Answer 11

To calculate the percentage uncertainty use
(Absolute uncertainty / Measurement value) x 100.

Question 12

What should you include when drawing a graph in an experiment (4)

Answer 12

• Labelled axes (with units).
• Title.
• Line of best fit.
• Data points plotted (with error bars if applicable).

Question 13

What is the purpose of a control experiment (3)

Answer 13

A control experiment is used to compare results.

• This helps to confirm that the effect on the dependent variable is due to the independent variable alone.
• This ensures that the results were obtained without any interference from other factors

Question 14

How do you ensure an experiment is reliable ?( 3)

Answer 14

• To ensure an experiment is reliable, repeat the experiment multiple times.
• Maintain consistent controlled variables.
• Use precise instruments

Question 15

What are systematic errors ? (2)

Answer 15

• Systematic errors are consistent, repeatable errors.
• They are caused by faulty equipment or flawed experimental design.

Question 16

How can systematic errors be minimised ? (3)

Answer 16

• Calibrate instruments.
• Use appropriate methods.
• Cross-check results with different methods

Question 17

Why is it important to calibrate instruments before taking measurements? (3)

Answer 17

• Calibrating instruments ensures that they provide accurate readings.
• This is done by comparing them to a known standard.
• Thereby, systematic errors are reduced.

Question 18

What is a colorimeter? (2)

Answer 18

• A colorimeter is apparatus that measures light absorbance or light transmission.
• It is used to measure colour change

Question 19

what questions are asked in a risk assessment? (3)

Answer 19

What could harm you?

• What harm could it cause you?
• What actions could be put in place to prevent / treat harm?

Question 20

What are some ways in which pH is measured? (3)

Answer 20

• Indicator paper.
• Indicator solution.
• pH metre.

Question 21

How is length measured

Answer 21

ruler
tape measure

Question 22

What needs to be considered when measuring length? (2)

Answer 22

• The scale needs to be considered.
• High enough precision of equipment should be ensured.

Question 23

How is temperature measured

Answer 23

thermometer
data logger

Question 24

How is volume of a gas measured

Answer 24

using a gas syringe

Question 25

How is volume of a solution measured ?

Answer 25

- measuring cylinder - syringe

Question 26

How is time measured ?

Answer 26

stop watch

Question 27

how is mass measured

Answer 27

using balances/scales

Question 28

What is an anomaly

Answer 28

an outlier in a set of results

Question 29

What is standard deviation (2)

Answer 29

- measures the spread of data around the mean value - this is useful when comparing consistency between diff data sets.