Why one mole of hydrogen molecules and one mole of H-atoms have different masses?

The number of grammes in a MOLE of any material is the same as the number of atomic mass units (amu). A mole of hydrogen atoms, on the other hand, has a mass of 1 gramme, while a mole of hydrogen molecules has a mass of 2 grammes. Remember that a hydrogen molecule is made up of two hydrogen atoms bound together.

Explanation:

the dissociation of nickel hydroxide is follows:

the concentration of hydroxide ion is

the equilibrium constant value of nickel hydroxide is = 6.1 * 10^-^1^6 and thus equilibrium equation can be written as:

thus, concentration of ni is 0.23 * 10^-^4 mol /l