Calcualte the number of moles of magnesium present in a magnesium ribbon weighting 12g. Molar atomic mass of magnesium is 24 g `mol^(-1)`.

Explanation

Given that molar atomic mass of Mg=24g `mol^(-1)`
24g of Mg = 1mol
12 g of Mg = `(1 xx12)/(24) = 1/2=0.5 mol`
Alternative Method
Number of moles of Mg `= ("Given mass")/("molar mass")=12g/(24g mol^(-1)) = 0.5 mol`