Difference between atomic number and atomic weight?

The nucleus contains protons and neutrons. ... The main difference between atomic number and atomic weight is that atomic number gives the number of protons present in the nucleus whereas atomic weight gives the mass of an atom.

Explanation:

Atomic number refers to the number of electrons or number of protons, both of which are the same. Atomic weight refers to the total mass of protons and neutrons in an atom, which are focused in the nucleus of the atom (and take most of the mass).

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.

i believe the answer is a.