Term 1 review: Units 1 to 4
Answers are for parents and teachers.
1
An atom has Z = 12 and A = 24. Give protons, neutrons and electrons, its arrangement, period and group.
12 protons, 12 neutrons, 12 electrons; 2, 8, 2; period 3, group 2A.
2
A girl rubs a balloon on her hair and it sticks to the wall. Explain in two sentences.
Rubbing moves electrons, so the balloon gets a static charge. It attracts the neutral wall.
3
A box has a mass of 8 kg. Find its weight on the Earth with g = 10 N/kg, and say what its mass is on the Moon.
80 N. The mass is still 8 kg.
4
Name two differences between photosynthesis and respiration.
Photosynthesis uses light and makes sugar; respiration releases energy from sugar.
5
Write a short note to explain to a friend why summer is warmer in Egypt, and why there is no lunar eclipse every month.
The tilt makes the Sun higher and the days longer. The Moon’s orbit is tilted by about 5°, so most full moons miss the Earth’s shadow.