Atoms of same element or of different elements can join together to form 

A group of atoms carrying a charge is known as 

 In a chemical substance, the elements are always present in definite proportions by mass.The law is

The ratio of given number of particles to Avogadro number gives

The ratio of given mass to the molar mass gives

The most remarkable concept that Dalton's atomic theory proposed was that of the

A group of atoms carrying a charge is known as 

The symbol of iron is 

The mass of 0.5 mole of N₂ gas is