How many moles are 5.55x10^25 atoms of Mg

Explanation:

To convert from atoms to moles, we must Avogadro's number:

This number tells us the amount of particles (atoms, molecules, etc.) in 1 mole of a substance. In this case, it is atoms of magnesium in 1 mole.

Now, let's set up an expression using:

Multiply this by the given number of atoms.

Flip the fraction so the atoms of magnesium can cancel.

Multiply and condense this into 1 fraction.

The original measurement had 3 significant figures, so our answer must have that many as well. For the number we calculated, that is the tenth place. The 6 in the hundredth place tells us to round the 1 to a 2.

It is about 92.2 moles of magnesium.

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explanation:

1.solid

2.carbon dioxide

3.helium