Asample of 508.4 grams of copper completely reacted with oxygen to form 572.4 grams of a copper oxide product. how many grams of oxygen must have reacted?

According to law of conservation of mass, mass can neither be destroyed nor created in a chemical reaction. Thus, sum of masses of reactants must be equal to sum of masses of products in a reaction.

The chemical reaction is as follows:

Here, sum of masses of Cu and oxygen gas should be equal to CuO formed.

Thus, mass of oxygen will be:

This can be further proved as follows:

The balanced chemical reaction is as follows:

Here, 2 moles of Cu completely reacts with 1 mole of to give 2 moles of .

Thus, 1 mole of Cu reacts with 0.5 moles of .

The mass of Cu is 508.4 and molar mass is 63.546 g/mol, number of moles can be calculated as follows:

Thus, number of moles of   reacting will be:

Molar mass of oxygen molecule is 32 g/mol thus, mass can be calculated as follows:

m=n×M=4 mol×32 g/mol=128 g/mol

This satisfies the law of conservation of mass.

explanation:

0.07 g/cm³

1.37 g/cm³

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.