(a) (i) What is refraction of light?
(ii) Sketch a diagram to show the path of a light ray when it travels from air to glass.

(b) Explain why it is difficult to separate iron and sulphur mixture after strong heating.

(c) (i) Give two example of digestive enzymes produced in humans.
(ii) For each of the enzymes given in (i), name the part of the human body where the enzyme is produced.

(d) List four methods of applying fertilizers to crops.