Answer: 5.08 moles
Step-by-step explanation:
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number
of particles.
To calculate the number of moles, we use the equation:

given mass of Cesium (Cs) = 675 g
Molar mass of Cesium (Cs) = 132.90 g/mol
Putting in the values we get:

Thus there are 5.08 moles of cesium in 675 g of cesium.