Which observation illustrates the law of conservation of mass?
the c: o mass ratio of a particular compound is the same, regardless of the size or source of the sample.
when 3 g of carbon reacts with 8 g of oxygen, 11 g of carbon dioxide is produced.
the c: o mass ratio of one compound is exactly double that of another compound.
burning 10 g of propane produces twice as much carbon dioxide as burning 5 g of propane.

When 3 g of carbon reacts with 8 g of oxygen, 11 g of carbon dioxide is produced.

Explanation:

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

Given: mass of carbon = 3 g

mass of oxygen = 8 g

Mass of products = Mass of carbon dioxide = 11 g

Mass or reactant = mass of carbon + mass of oxygen = 3 g  + 8 g = 11g

Thus the total mass of reactants is equal to the total mass of products.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-

a polar bond is formed when electrons are shared unevenly between atoms