Question

13 which chemical reaction below best represents the law of conservation of mass?

Explanation:

Step1: Count atoms in reactants and products for option A

Reactants: 2 white atoms (from first molecule) + 2 dark atoms (from second molecule). Products: 2 white atoms + 2 dark atoms.

Step2: Count atoms in reactants and products for option B

Reactants: 1 dark + 1 white (from first molecule) + 2 white (from second molecule) = 1 dark + 3 white. Products: 2 dark + 3 white. Atoms not conserved.

Step3: Count atoms in reactants and products for option C

Reactants: 1 white + 2 dark. Products: 1 white + 1 dark. Atoms not conserved.

Step4: Count atoms in reactants and products for option D

Reactants: 1 dark + 2 white. Products: 1 dark + 2 white. But in reactants, one dark is single - atom, in products it's part of a molecule. But by atom count (not molecule count), A has correct atom - by - atom conservation as per Law of Conservation of Mass (atoms are neither created nor destroyed in a chemical reaction, only rearranged).

Answer:

A