Question

Name any three methods of separating substances in dry conditions, and define them. [3 MARKS]

Answer 1

Definitions: 1 Mark each

Any three:
Handpicking
It involves simply picking out substances by hand and separating them from other substances.

Threshing
This is done after harvesting of crops. Once wheat is harvested, the stalks are dried. Then, the dry stalks are beaten so that the dried grains inside the stalks shake off and fall out.

Winnowing
It is the process of clearing the grains of the husk and chaff before grinding into flour. The farmer gently drops the mixture to the ground from a height. The heavier grains are collected at a place, while the lighter chaff blows away.

Sieving
Sieving is used to separate substances that are of different sizes. It is also called filtering. In this method, a sieve is used. The smaller components of the mixture can pass through the pores of the sieve whereas bigger components of the mixture are retained by the sieve.