PTS Science K8 S1

Zaid draws a diagram of an atom of lithium.

Explain why the electrons in the charge cloud cannot escape from the atom. Use ideas about the charges on the particles in the atom. [2]

Zaid wants to draw a diagram of an atom of sodium. Describe how an atom of sodium is different from an atom of lithium. Choose the correct answer.

• different number of electrons

• different number of protons

• different size of atom

• defferent size of neutron

The drawings, based on fossils, show an iguanodon and a woolly mammoth.

These animals both lived in the same parts of Europe but at different times. Both animals are now extinct. Scientists think that the Earth’s climate cycles between warm and cold periods of time.

Does the fossil evidence support the idea that the Earth has cycles of warm and cold periods of time? Give reasons for your answer. [2]

Yuri runs a 100 m race. He takes 13 seconds to run 100 m. Calculate Yuri's average speed. Include the units in your answer.

Yuri does a run. Look at the distance / time graph for Yuri’s run. Between which points does Yuri stop for a rest?

• A and B

• B and C

• C and D

• D and E

Safia investigates how changing the temperature affects the volume of a gas. She places a sealed balloon in water at two different temperatures.

She uses water at 10 °C and at 50 °C. She measures the diameter of the balloon at both temperatures.

Predict what happens to the diameter of the balloon as the temperature of the water increases. Explain your answer. Use ideas about particles.

Which of these are correct statements about the electrical charges of subatomic particles.

• proton has positive (+) charge

• nucleus has negative (-) charge

• electron has negative (-) charge

• neutron has no (0) charge

What is the name of the part of the atom that contains the protons and neutrons?

What is an ecosystem?

European rabbits were introduced into Australia as a source of food for humans in the late 1700s. The number of rabbits increased rapidly. They became pests and damaged the ecosystems in large parts of Australia. Suggest two reasons why the number of rabbits increased so rapidly.