Question

A mole is defined as:

• A. molecular weight expressed in grams
• B. molecular weight divided by $1g$ of $H_2$
• C. number of particles contained in $12g$ of $C$ of atomic mass $12$
• D. number of molecules contained in one litre of a gas at S.T.P

Answer 1

Answer: (A)

molecular weight expressed in grams

The mole is a unit of measurement for amount of substance. It is defined as the amount of any chemical substance that contains as many elementary entities e.g.atoms, molecules, ions, electrons or photons like atoms present in 12 gm of pure carbon with relative atomic mass 12. It has the unit symbol mol. The number of molecules in a mole is defined such that the mass of one mole of a substance expressed in grams is equal to mean molecular mass of the substance.