Answer : The percent of aluminium in 
 is
 is 

Solution :
Molar mass of Aluminium = 26.98 g/mole
Molar mass of 
 = 342.15 g/mole
 = 342.15 g/mole
First we have to calculate the mass of Aluminium.
Mass of 2 Al atoms = 2 × 26.98 g/mole = 53.96 g/mole
Now we have to calculate the percent composition of Aluminium in 


Now put all the given values in this formula, we get 


Therefore, the percent of aluminium in 
 is
 is 
