What is the mass number of an element, the atom of which contains two Protons, two neutrons and two electrons? 

The maximum number of electrons that can be accommodated in M shell is:

Potassium nitrate is used in

Water gas is the mixture of 

Gasohol is – 

The air is the example of:

Atomic number of which of the following elements is greater than that of Copper?

What do you call the type of drugs that mimic the natural messenger by switching on the receptor?