Question

copper oxide gives two oxide on heating 1.0 gram of each in hydrogen gas 0.888 gram and 0.799 gram of the metal are produced so that the results agree with the law of multiple proportion

Answer 1

let the two oxides of Cu be named A and B
oxide A
mass of Cu in 1g of oxide A = 0.888g 
mass of O in 1g of oxide A =1-0.888=0.112g
oxide B
mass of Cu in 1g of   oxide B = 0.799g
mass of O in g of oxide B = 1-0.799=0.201g
In oxide A , 1g Cu is combined with oxygen = 0.112 x 1/0.888 = 0.126g
In oxide B , 1g Cu is combined with oxygen = 0.201 x 1/0.799 = 0.252g
the different weight of oxygen combined with a fixed weight (1g) of Cu are in ratio 0.126 : 0.252  or 1: 2
This is a simple whole ratio that shows the agree with the law of multiple properties .

Answer 2

HEY MATE!!

let the two oxides of Cu be named A and B

oxide A

mass of Cu in 1g of oxide A = 0.888g

mass of O in 1g of oxide A =1-0.888=0.112g

oxide B

mass of Cu in 1g of   oxide B = 0.799g

mass of O in g of oxide B = 1-0.799=0.201g

In oxide A , 1g Cu is combined with oxygen = 0.112 x 1/0.888 = 0.126g

In oxide B , 1g Cu is combined with oxygen = 0.201 x 1/0.799 = 0.252g

the different weight of oxygen combined with a fixed weight (1g) of Cu are in ratio 0.126 : 0.252  or 1: 2

This is a simple whole ratio that shows the agree with the law of multiple properties .

HOPE IT HELPS!