Questions

The comma ( , ) is a punctuation mark in English which is most frequently used.

It is perhaps also the most abused and misused punctuation mark among all.

Black  surfaces are good emitters of heat ( They are also good absorbers of heat). If the black surface is rough too, the emitting will be better. So (b) is the correct answer. Shining surfaces reflect back radiation. So if the black surface is also shining the effectiveness of emitting heat is lessened.

without this centripetal force, circular motion is not possible. It acts radially towards the centre and if this force is removed there will be no circular motion but the revolving body will fly off at a tangent.

A Hole gets bigger and bigger as you take more away from it.

The first written story that has come down to us is The Epic of Gilgamesh.

It is a mythologized account of a historical figure, Gilgamesh, a ruler of the Sumerian city-state of Uruk, believed to have ruled sometime between 2700-2500 BC.

Proteins are long chains of Amino acids. That is in brief, Amino acids are the monomers of Proteins. Amino acids are compounds which contain both an amino group and a carboxylic group. Proteins are made up of 20 essential amino acids.

Monomer means a small molecule of an organic substance i.e, building block in general.