92 GENERAL SCIENCE 



14. Do babies breathe through the nose or mouth? 



15. What should be done when children are found to have the 

 habit of mouth breathing? 



16. How does dust affect the normal functioning of the lungs? 



17. Why are mouth breathers more susceptible to contagious 

 diseases? 



18. Is breathing voluntary or involuntary? 



19. In what respects does exhaled air differ from inhaled air? 



