Question

give reason- the dough prepared for making idli rises when kept overnight

Answer 1

The dough prepared for making idli rises when kept overnight because of the production of carbon dioxide gas in it. This gas is produced as a byproduct of process of fermentation (anaerobic respiration/respiration in absence of oxygen) in batter of black lentils or rice which is used to make idli. The fermentation process breaks down starches in batter into acid along with release of carbon dioxide.