Answer: There are [tex]4.13 \times 10^{-3}[/tex] moles of Pb are contained in [tex]2.49 \times 10^{25}[/tex] atoms Pb.
Explanation:
According to the mole concept, 1 mole of every substance contains [tex]6.023 \times 10^{23}[/tex] atoms.
Hence, number of moles present in [tex]2.49 \times 10^{25}[/tex] atoms of Pb are as follows.
[tex]No. of moles = \frac{2.49 \times 10^{25}}{6.023 \times 10^{23}}\\= 4.13 \times 10^{-3} mol[/tex]
Thus, we can conclude that there are [tex]4.13 \times 10^{-3}[/tex] moles of Pb are contained in [tex]2.49 \times 10^{25}[/tex] atoms Pb.