A sample of crushed rock is found to have 4.81 x10^21 atoms of gold, how many moles of gold are present in this sample? a) 7.99 x 10^-3 moles
b) 1.57 x 10^-1 moles
c) 1.25 x 10^3 moles
d) 2.47 x 10^5 moles

0.8 moles

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

\begin{gathered}n = \frac{N}{L} \\\end{gathered}

n=

L

N

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

We have

\begin{gathered}n = \frac{4.81 \times {10}^{23} }{6.02 \times {10}^{23} } = \frac{4.81}{6.02} \\ = 0.799003...\end{gathered}

n=

6.02×10

23

4.81×10

23

=

6.02

4.81

=0.799003...

We have the final answer as

0.8 moles

Hope this helps you

hurricanes form when warm, moist air from the ocean surface quickly rises into the atmosphere and forms storm clouds and rain. when the clouds are formed, heat is released which warms the cool air in the upper regions of the atmosphere so that the cycle can continue. which two phases of the water cycle are repeated in this process?