Name the source from which nitrogen and oxygen are obtained on a large scale.

Name one pair of liquids which can be separated by using a separating funnel.

State whether the following statements are true or false:

(a) Alcohol can be separated from a mixture of alcohol and water by a separating funnel.

(b) Salt and water can be recovered from an aqueous salt solution by the process of evaporation.

Name the process by which the various gases of the air are separated.

A carpenter wants to separate iron nails from saw-dust. Which method of separation should he choose?