Questions

It's a logic question. The answer can be

Boy can propose because he is not blind,deaf n dumb. It was not mentioned that the girl have to understand his proposal.

The process of conversion of milk into curd is called fermentation.  It is a chemical change. Milk consists of globular proteins called casein. As the microorganism lactobacillus react with milk and turn it to curd. For it 37 degree temperature is needed. But sometimes when it does not get favourable condition, then other microorganism react and makes the curd taste different.

Silence is what is so delicate that even mentioning it breaks it.

Silver nitrate is the basic substance from which silver bromide is obtained. The photographic films are impregnated with the light sensitive AgBr.

Monoculture is a typical characteristics of Commercial grain farming.

Monoculture is the agricultural practice of producing or growing a single crop, plant, or livestock species, variety, or breed in a field or farming system at a time focussing commercial gains.

Monoculture is widely used in both industrial farming and organic farming and has allowed increased efficiency in planting and harvest.

Polyculture, where more than one crop is grown in the same space at the same time, is the alternative to monoculture.