How many moles of potassium are in 3.78 x 10^21 atoms of K?

6.3 x 10^-3 moles

Explanation:

Based on Avogadro's law:

1 mole of any substance has 6.02 x 10^23 atoms

So, 1 mole of potassium = 6.02 x 10^23 atoms

Z moles = 3.78 x 10^21 atoms

To get the value of Z, we cross multiply:

(3.78 x 10^21 atoms x 1mole) = (6.02 x 10^23 atoms x Z moles)

3.78 x 10^21 = (6.02 x 10^23 x Z)

Z = (3.78 x 10^21) ➗ (6.02 x 10^23)

Z = 0.63 x 10^-2)

Place the result in standard form

Hence, Z = 6.3 x 10^-3 moles

Thus, there are 6.3 x 10^-3 moles of potassium in 3.78 x 10^21 atoms of K.

the answer is b & c i believe : )

it is the most commonly accepted one