Explanation:
It is known that a mole of carbon atom contains a mass of 12 g and a mole of oxygen atom contains a mass of 16 g.
As it is given that first compound has 27.2 g C. So, amount of oxygen present in this compound will be as follows.
(100 - 27.2) g
= 72.8 g of O
Hence, calculate the moles of C and O as follows.
No. of moles of C = 
= 
= 2.26 mol
No. of moles of O = 
= 
= 4.55 mol
Therefore, mole ratios of both C and O will be calculated as follows.
C = 
= 1
O = 
= 2
Hence, empirical formula of the first compound is
.
Since, it is also given that mass of carbin in another compound is 42.9 g. So, mass of oxygen present will be as follows.
(100 - 42.9) g
= 57.1 g
Hence, calculate the moles of C and O as follows.
No. of moles of C = 
= 
= 3.57 mol
No. of moles of O = 
= 
= 3.57 mol
Therefore, mole ratios of both C and O will be calculated as follows.
C = 
= 1
O = 
= 1
Hence, empirical formula of the second compound is CO.
Therefore, carbon and oxygen combine to form 2 different compounds in small whole numbers.