Question

When water decomposes into oxygen and hydrogen, the mass

A. remains constant.
B. decreases.
C. varies according the number of hydrogen and oxygen molecules that form.
D. increases.

Answer 1

When water decomposes into oxygen and hydrogen, the mass "Remains Constant" as according to Law of Conservation of mass, mass can neither be created not destroyed,.

In short, Your Answer would be Option A

Hope this helps!