How many grams of magnesium will have the same number of atoms as 6 grams of carbon ?
`(Mg = 24 u , C = 12 u )`

Explanation

First we need to calculate the number of atoms in 6 g of C.
1 gram atomic mass of carbon = 12 g of carbon
`= 6.022 xx10^(23)` atoms
`:. 6g` of carbon contains
`=(6.022 xx 10^(23))(12)xx6` atoms `= 3.011xx 10^(23)` atoms.
1 gram atomic mass of magnesium
= 24 g of magnesium `= 6.022xx 10^(23)` atoms
`6.022 xx 10^(23)` atoms are present in 24 g of Mg
`: 3.011 10^(23)` atoms are present in
`=(24)/(6.022 xx 10^(23)) xx 3.011xx10^(23) = 12 g`
` :.. 12 g `of magnesium will have the same number of atoms as `C(3.011xx10^(23))`