How does the law of conservation of mass apply to this reaction C2H4 + O2 > 2H2O + 2CO2 ?
A.Only the oxygen needs to be balanced
B. The equation needs to be balanced. There are fewer oxygen atoms in the equation than hydrogen and carbon
C.The law of conservation of mass has already been applied
D. Each element needs to be balanced

Respuesta :

The answer is A, only the oxygen needs to be balanced.
There is an even amount of hydrogen atoms and carbon atoms on both sides, but there are two atoms of oxygen on the left side and four on the right. 
There needs to be an even, or balanced, amount of oxygen to make to formula correct.
A.Only the oxygen needs to be balanced

Hydrogen & Carbon has already balanced in the equation.

Hope this helps!