Can someone tell me the answer and plz no wrong answers

D, a tool too organize the elements

Explanation:

If it were a list, it would be unorganized and not in atomic number or by mass. So A is wrong. It isn't a method to name elements, they are named by their founders who made the discoveries so B and C are both wrong. D must be correct because they are organized in a manner where they are by mass, atomic number, and into their respective groups (alkali metals, alkali earth metals, transition metals, lanthanides, actinides, poor metals, semi metals, non-metals, and noble gases)

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.

it forms an anion that has a larger radius. anions have a negative charge and are larger than the original atom.