The roof of the nasal cavity is formed by which bone?

The path of air during respiration is:

Match the following columns:

Column-$I$	Column-$II$
$a$. Larynx	$p$. Epiglottis
$b$. Trachea	$q$. Alveoli
$c$. Alveolus	$r$. Sound box
$d$. Epiglottis	$s$. Air passage tube
	$t$. Common passage

Select the correct statements about alveoli from the following.
$i$. Air sac of each terminal bronchiole shows $10$ to $12$ alveoli.
$ii$. Each alveolus is surrounded by a network of capillaries.
$iii$. They are lined by ciliated pseudostratified epithelium.
$iv$. They provide surface area for exchange of gases.
$v$. There are about $700$ million alveoli in the lungs.

Identify the component of the respiratory system which displays the features given below and choose the correct option:
$I.$ Double layered
$II.$ Fluid contained in it reduces the friction on the lung surface
$III.$ Its outer layer is in contact with the thoracic wall
$IV.$ Its inner layer is in contact with the lungs

The alveolar sac of the lungs and the villi of the intestine have a similar function,which is that: