Which equation shows conservation of atoms?
a) h2 + o 2 --> h2o
b) h2 + o 2 --> 2h2o
c) 2h2 + o2 --> 2h2o
d) 2h2 + 2o2 --> 2h2o

The equation showing conservation of atoms is

Explanation:

Every balanced chemical equation follows law of conservation of mass.

This law states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form. This also means that total number of individual atoms on reactant side must be equal to the total number of individual atoms on the product side.

For the given chemical equations:

The given chemical equation follows:

There are 2 hydrogen atoms and 2 oxygen atoms on the reactant side and 2 hydrogen and 1 oxygen atom on product side.

So, this equation does not show conservation of atoms.

The given chemical equation follows:

There are 2 hydrogen atoms and 2 oxygen atoms on the reactant side and 4 hydrogen atoms and 2 oxygen atoms on product side.

So, this equation does not show conservation of atoms.

The given chemical equation follows:

There are 4 hydrogen atoms and 2 oxygen atoms on the reactant side and 4 hydrogen atoms and 2 oxygen atoms on product side.

So, this equation shows conservation of atoms.

The given chemical equation follows:

There are 4 hydrogen atoms and 4 oxygen atoms on the reactant side and 4 hydrogen atoms and 2 oxygen atoms on product side.

So, this equation does not show conservation of atoms.

Hence, the equation showing conservation of atoms is