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

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3