Hi class,
These are the answers for the practice paper.

41a) Beaker A
41b The trapped air in the beakers takes up space but beaker Q has a glass tube to allow air to escape, thus causing the oil to flow in faster.
41c) He can add one (or) more hole on top of the can.

42a) (Number must be more than 1mm but less than 6mm)
42b) The set up would be the same but without cockroaches.
42c) It will be used to check if the reading shown on the ruler would change without respiration taking place in the test tube.
42d) Yes. Ants respire too.

43a) The paper clip would be attracted to the iron rod.
43b) Her earrings are made of a non-magnetic material.
43c) She could increase the number of batteries / coils around the iron rod.

44a) The balance will tilt downwards at B.
44b) 10 litres
44ci) Air has mass.
44cii) Air can be compressed.

Study hard and good luck for your Science examination tomorrow.