You are aware of the $Polio$ $Eradication$ $Programme$ in your city. Children are vaccinated because:

Justify the following statements:
$(a)$ "Availability of proper and sufficient food would prevent infectious diseases."
$(b)$ "The general ways of preventing infection mostly relate to preventing exposure." List three points of prevention of exposure.

Which disease is not transmitted by mosquitoes?

Making anti-viral drugs is more difficult than making anti-bacterial medicines because

Which of the following can make you ill if you come in contact with an infected person?

Raju of Class $IX$ was suffering from chickenpox. His friends Priya and Shaurya wanted to visit him. Shaurya's parents did not allow him to go. Priya had already suffered from it a few months before. Priya's parents allowed her to visit him. What could be the reason behind their parents' decision? What is the basis of the principle of immunisation?