Find the mass of 12.044 x 10²³ atoms of megnesium.

(given -> atomic mass of Mg =24.0u)

In order to calculate the unit mass (in gms) of any substance we simply divide its molecular/atomic mass by the Avagadro's Number.

So,

the mass of 1 atom of Mg = 24 / 6.023 X 10^-23 gm

or

the mass of 12.044 X 10^-23 atoms will be = 12.044 X 10^-23 X (24 / 6.023 X 10^-23) gms = 2 X 24 gms

thus,

the mass is 48 gms