Here's how to calculate the number of moles of PbSO₄ in the bottle:

1. Find the molar mass of PbSO₄:

* Lead (Pb): 207.2 g/mol

* Sulfur (S): 32.06 g/mol

* Oxygen (O): 16.00 g/mol (and there are four oxygen atoms)

Molar mass of PbSO₄ = 207.2 + 32.06 + (16.00 x 4) = 303.26 g/mol

2. Calculate the number of moles:

* moles = mass / molar mass

* moles = 158.1 g / 303.26 g/mol

* moles ≈ 0.521 mol

Therefore, there are approximately 0.521 moles of PbSO₄ in the bottle.