How do balanced chemical equations thon the conservation of mass?
They show that the atoms in the products
may be different than the readarts as long
as the mass does not change,
They show that the atoms in the products are
the same as in the reactants, but the number
of atoms must change,
They show that the number of atoms of each
element is the same in the products and
reactants

They show that the number of atoms of each  element is the same in the products and  reactants

Explanation:

Balanced chemical equations show the conservation of mass in that the number of atoms of each element is the same in the products and reactants.

where's the diagram?

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.