Tin (sn) exists in earth's crust as sno2. calculate the percent composition by mass of sn and o in sno2.

Sn = 78.77%

O = 21.23%

Explanation:

The atomic mass of Sn = 118.71 g/mol

The atomic mass of O = 16 g/mol

The molar mass of SnO₂ = atomic mass of Sn + 2 X atomic mass of O

The molar mass of SnO₂= 150.71

Now, in each mole of SnO₂ there is one mole of Sn and two moles of O

The mass of Sn in 150.71 g of SnO₂ = 118.71

Percentage of Sn in 150.71 g of SnO₂ =

% of Sn = %.

Rest will be O = 100-78.77 = 21.23%