(a) (i) What is an ion?
(ii) State two methods of softening hard water.

(b) (i) Differentiate between pests and parasites as used in agriculture.
(ii) Give an example each of a:
(α) pest;
(β) parasite

(c) (i) What is work?
(ii) A force of 10 N causes a body to move a distance of 5.2 m in the direction of the force. Calculate the work done.

(d) Name two diseases associated with the circulatory system of humans