Work through these eight questions in order, and write your own answer before you open each one. They cover all four lessons in laboratory safety and investigation.
The timed practice session builder can turn the set into a timed run.
Questions
Question 1 (1 mark). A bottle has a flammable symbol. State what this symbol warns of.
Answer
The substance catches fire easily.
Question 2 (2 marks). Give one precaution for handling a corrosive liquid and link it to the hazard.
Answer
Wear goggles and gloves, because a corrosive liquid damages skin and eyes.
Question 3 (2 marks). A student needs exactly 40 cm³ of water. Name suitable apparatus and give a reason.
Answer
A measuring cylinder, because it has a scale with small divisions and gives a measured volume. A beaker gives only a rough guide.
Question 4 (2 marks). What apparatus measures the time a trolley takes to roll down a ramp, and why?
Answer
A stopwatch, because the time is short and needs to be read to a fraction of a second.
Question 5 (3 marks). Tariq tests whether the length of a pendulum string changes the time for 10 swings. State the manipulated variable, the responding variable and one fixed variable.
Answer
Manipulated: length of the string (cm). Responding: time for 10 swings (s). Fixed: mass of the pendulum bob, or the angle the bob is released from.
Question 6 (3 marks). Three plants are placed in a dark cupboard, a bright window and a dim corner. The plant in the window also gets 50 cm³ of water, while the others get 20 cm³. Explain why the test is unfair and how to correct it.
Answer
Two factors differ, the light and the volume of water. So any change in growth cannot be blamed on light alone. Give every plant 20 cm³ of water each day, so only light differs.
Question 7 (2 marks). A thermometer has divisions of 1 °C. The liquid sits exactly on the 34 mark. Write the reading, and explain why 34.0 °C is not better.
Answer
The reading is 34 °C. Writing 34.0 °C suggests the instrument can measure to 0.1 °C, which it cannot.
Question 8 (4 marks). A 100 cm³ measuring cylinder holds water. A stone is lowered in and the level rises from 62 cm³ to 75 cm³. State the volume of the stone, then explain why the student should read the bottom of the meniscus with the eye level with the scale.
Answer
Volume = 75 − 62 = 13 cm³.
Reading the bottom of the curve at eye level avoids parallax error. If the eye is above or below the scale, the reading appears higher or lower than it really is.
If you got these wrong
- Questions 1 and 2: revisit interpreting hazard symbols.
- Questions 3 and 4: revisit selecting suitable apparatus for a task.
- Questions 5 and 6: revisit identifying variables and fair comparisons.
- Questions 7 and 8: revisit reading measurements and reporting units.
Log each slip in the mistake log and paper-error review. To practise with a teacher, see online one-to-one Science tuition.