What is the relation between the value of the unified atomic mass unit in grams and the valueof Avogadro’s constant in mol-1 ?

The relationship between the unified atomic mass unit (u) and Avogadro's constant (NA) is quite direct.

1. The unified atomic mass unit (u) is defined as 1/12th the mass of a carbon-12 atom. It is approximately equal to 1.660539040(20) x 10^-24 grams.

2. Avogadro's constant (NA), on the other hand, is the number of atoms in one mole of a substance. It is approximately equal to 6.02214076 x 10^23 mol^-1.

3. The relationship between these two values is that if you multiply the atomic mass unit (in grams) by Avogadro's constant, you get the molar mass of an element in grams/mol. This is because Avogadro's constant represents the number of atoms in a mole, and the atomic mass unit represents the mass of one atom.

So, when you multiply them together, you get the mass of one mole of atoms, which is the definition of molar mass. This relationship is a fundamental one in chemistry, and is used in many calculations involving moles, atoms, and mass.