Question

Mass of 2 x 1021 number of atoms of a

Answer 1

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 $6.022 \times 10^{22}$. As, the mass of $2 \times 10^{21}$ atoms is 0.49 g.

So, $\frac{2 \times 10^{21}}{6.022 \times 10^{23}} mol = 0.49 g$

$0.003 mol = 0.49 g$

Therefore, mass of 1 mole = $\frac{0.49}{0.003}$

                                            = 163.33 g/mol

Hence, mass of 0.5 mole of ab element is calculated as follows.

$0.5 mol \times 163.33 g/mol$

= 81.67 g

Therefore, the mass of 0.5 mole of element ab is 81.67 g.