Chlorophyll, the green colouring matter of plants contains 2.68% magnesium by weight. Calculate the number of magnesium atoms in 2.00 g of chlorophyll (Atomic mass Of Mg = 24).
Mass of chlorophyll = 2.0 g
Percentage of Mg = 2.68 g
2 68 x 2 0
Mass of Mg in 2.0 g of chlorophyll = 2.69 x 2.0/100= 0.054 g
6.022 X ${{10}^{23}}$ atoms of magnesium = 24 g
.’. 24 g of Mg contains 6.022 X ${{10}^{23}}$ atoms
0.054 g of Mg contains 6.022 X ${{10}^{23}}$/24 x 0.054
= 1.3x ${{10}^{21}}$ atoms