State any two conditions essential for being free of disease.

What is immunisation?

State any two conditions essential for good health.

Under which of the following conditions is a person most likely to fall sick?
$(a)$ When she is recovering from malaria.
$(b)$ When she has recovered from malaria and is taking care of someone suffering from chicken-pox.
$(c)$ When she is on a four-day fast after recovering from malaria and is taking care of someone suffering from chicken-pox.
Why?

Conduct a survey in your neighbourhood to find out what the three most common diseases are. Suggest three steps that could be taken by your local authorities to bring down the incidence of these diseases.

Under which of the following conditions are you most likely to fall sick?
$(a)$ When you are taking examinations.
$(b)$ When you have travelled by bus and train for two days.
$(c)$ When your friend is suffering from measles.
Why?