Answer:
53.2%
Explanation:
Mass of Si in 1 mol SiO2 =28.1g
Mass of O in 1 mol SiO2 =16x2g= 32g
Mass of compound= 28.1+32=60.1
% by mass = (mass of element/mass of compound) x 100
% by mass of oxigen= (32g/60.1) x 100
% by mass of oxigen= 53.2%
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