How many moles are in 7.777x 10^24 molecules of Mg2. Watch your significant
figures

12.91 moles of Mg₂, 8.4x10²⁴ atoms of I.

Explanation:

The number of molecules of any chemical substance is converted to moles using Avogadro's number (That is 6.022x10²³ molecules / mol) :

7.777x10²⁴ molecules * (1mol / 6.022x10²³molecules) =

As you can see, there are 4 significant figures in the number of molecules and the answer of moles.

In the same way, 14 moles of I are:

14 moles I * (6.022x10²³ atoms / mol) =

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