Question

Give reason .. A. Lungs always contain residual volume . B. Nostrils are lined with mucus plz answer

Answer 1

b. nostrils are lined with mucus bcz the sticky mucus present in our nose traps the dirt and dust which tries to enter our body through our nose

Answer 2

for B.
Harmful substances and germs get trapped in the hair and mucus present inside the nose. In this way, they help in filtration of air inhaled. The germs that escape are trapped by mucus and cilia in air passages. The mucus in the cells of trachea and bronchial tubes keep the passages moist and clean and the air filtered.
Hope it helps!