Can someone me! i really don't understand this

1 mole of peroxide (H₂O₂)

Explanation:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

1.008 g of hydrogen = 1 mole = 6.022 × 10²³ atoms of hydrogen

One mole of peroxide contain two mole of oxygen atom. Thus,

one mole oxygen atom = 6.022 × 10²³ atoms

For two mole oxygen atoms:

2×6.022 × 10²³ atoms

1.2× 10²⁴ oxygen atoms

indium, and thallium have three electrons i think