Answer: The mass of 0.5 mole of element ab is 81.67 g.
Explanation:
According to the mole concept, 1 mole of a substance contains [tex]6.022 \times 10^{22}[/tex]. As, the mass of [tex]2 \times 10^{21}[/tex] atoms is 0.49 g.
So, [tex]\frac{2 \times 10^{21}}{6.022 \times 10^{23}} mol = 0.49 g[/tex]
[tex]0.003 mol = 0.49 g[/tex]
Therefore, mass of 1 mole = [tex]\frac{0.49}{0.003}[/tex]
= 163.33 g/mol
Hence, mass of 0.5 mole of ab element is calculated as follows.
[tex]0.5 mol \times 163.33 g/mol[/tex]
= 81.67 g
Therefore, the mass of 0.5 mole of element ab is 81.67 g.
