1. Chemical Formula:

* Ammonium sulfide has the chemical formula (NH₄)₂S.

2. Hydrogen Atoms per Molecule:

* Each ammonium ion (NH₄⁺) has 4 hydrogen atoms.

* There are two ammonium ions per molecule of ammonium sulfide.

* Therefore, there are 4 * 2 = 8 hydrogen atoms per molecule of ammonium sulfide.

3. Avogadro's Number:

* One mole of any substance contains Avogadro's number of particles (6.022 x 10²³).

4. Calculation:

* Step 1: Calculate the number of ammonium sulfide molecules: 3.40 mol * (6.022 x 10²³ molecules/mol) = 2.05 x 10²⁴ molecules

* Step 2: Multiply the number of molecules by the number of hydrogen atoms per molecule: 2.05 x 10²⁴ molecules * 8 hydrogen atoms/molecule = 1.64 x 10²⁵ hydrogen atoms

Answer: There are approximately 1.64 x 10²⁵ hydrogen atoms in 3.40 mol of ammonium sulfide.