Question

7 kg of gold was recovered from a smuggler. How many atoms of gold were recovered ? (au 197) (a) 100 (b) 6.02x 1023 (c) 6.02x 1024 (d) 6.02 x 1025

Answer 1

Answer: 2.140*10^25 atoms

Explanation:

Answer 2

Given: 7 kg of gold was recovered from a smuggler.

To find: The atoms of gold recovered.

Solution:

The mass of gold = $7 kg$

                             $& =(7\times 1000)g \\ & =7000g$

It is known that the atomic mass of gold is 197 g/mol.

∴ The number of moles of gold present in 7000g of gold

                                                    = $\frac{weight of the element}{molecular weight of the element}$

                                                    = $\frac{7000g}{197g/mol}$

                                                    =$35.53 moles$

Now, we know that, Avogadro's number = $6.023\times {{10}^{23}}$, which is a constant number.

∴The number of atoms of golds present in 35.53 moles =$35.53\times 6.023\times {{10}^{23}}$

                                                                                             = $213.99\times {{10}^{23}}$

Hence, the number of atoms of golds recovered were $213.99\times {{10}^{23}}$.

Note: The options does not match due to mistake in data.