Final answer:
Approximately 1.5055 x 10^23 atoms of Rb are in 0.250 moles of Rb.
Step-by-step explanation:
The question asks how many atoms are in 0.250 moles of Rb.
To solve this, we can use Avogadro's number, which states that 1 mole of any substance contains approximately 6.022 x 10^23 particles (atoms or molecules).
Therefore, in 0.250 moles of Rb, there would be approximately 0.250 x 6.022 x 10^23 = 1.5055 x 10^23 atoms of Rb.