100+ Transformation of Substances Question Answer - 2

Question: 6

What is fermentation?

Milk turns into curd by the action of enzymes. This chemical change is called fermentation.

Question: 7

What is distillation?

Distillation is a method of purification of a liquid containing volatile impurities. This method involves evaporation and condensation. It is a process of converting a liquid into vapour and then condensing the vapour to get back the pure liquid separately.

Question: 8

What is a reduction reaction?

A chemical reaction which involves addition of hydrogen to a substance or removal of oxygen from a substance is called reduction reaction.

Question: 9

Define endothermic change?

A reaction during which heat is absorbed is called endothermic reaction. When sodium nitrate is added to some water in a beaker, the temperature of water falls down. This is an example for endothermic reaction.

Question: 10

Mention some techniques of purification?

Distillation, fractional distillation, sublimation and filtration are some of the techniques of purification.