How does the law of conservation of mass apply to this reaction: c2h. + 02 + h2o + co2?
only the oxygen needs to be balanced. there are equal numbers of hydrogen and
carbon
each element needs to be balanced.
the equation needs to be balanced. there are fewer oxygen atoms in the equation than
hydrogen or carbon
the law of conservation of mass has already been applied. there is an equal number of
each element on both sides of the equation.

This is incorrect equation because C₂H is not true formula. The valency of carbon is not satisfied.

The equation may be

C₆H₁₂O₆ + O₂ → CO₂ + H₂ O

In this equation each element is need to be balanced.

Explanation:

Law of conservation of mass:

According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.

Explanation:

This law was given by french chemist  Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.

For example:

In given reaction:

C₆H₁₂O₆ + O₂ → CO₂ + H₂ O

In this equation each element is need to be balanced.

Balanced chemical equation:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂ O

In this equation each element is balanced on both side of equation.