Why during rainy seasons, the wooden doors and windows are difficult to closs and open ? Give the phenomenon behind this and also define the phenomenon.

Explanation

(i) The grills of doors and windows are generally made of the metla iron.
(ii) When they are exposed to air, due to the effect of moisture in air, iron undergoes slow oxidation reaction and forms a layer of reddish brown rust which gets deposited on the surface of girlls.
(iii) Thus, due to the reaction of slow process of decay or destruction of metal iron, the girls of doors and windows made of metal iron get corroded.
(iv) Hence, in order to prevent the ruse and corrosion, girls of doors and windows are always painted befor they are used.
(v) By doing this, air and moisture cannot come in contact with the iron and hence rusting doesn't take place.