How many hydrogen atoms are in 8.90 mol of ammonium sulfide?

The number of hydrogen atoms in 8.90 mol of ammonium sulfide is  4.28×10²⁵ atoms.

This is referred to as a proportionality factor which tells us about the number of constituent particles in a sample. The constant is  6.02ₓ 10²³.

Ammonium sulfide which is denoted as (NH4)₂S has 2 nitrogen, 8 hydrogen and 2 sulfur atoms present.

We were told that the amount of ammonium sulfide is 8.90mol.

Number of hydrogen atoms =  8/1 × 8.9 mol= 71.2 moles of H₂.

The number of Hydrogen atoms in  8.90 mol of ammonium sulfide is 71.2 moles ˣ 6.02ˣ 10²³ = 4.28 ˣ10²⁵ atoms.

Read more about Avogadro's constant here link

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.