Question

How many moles of Cr are in 2.16 mol of Cr2O3?

Answer 1

When 1 mol of Cr2O3 has 2 mol of Cr, So we can easily get the number of moles of Cr in  2.16 mol of CrO3 by:
Cr     → Cr2O3
2 mol→ 1 Mol
 X      → 2.16 Mol
So X (the no. of mol of Cr ) = 2 Mol * 2.16 Mol = 4.32 Mol

Answer 2

Answer:There are 4.32 moles of Cr in 2.16 moles of  $Cr_2O_3$.

Explanation:

Moles of $Cr_2O_3$ = 2moles

In one molecule of $Cr_2O_3$ there are 2 atoms of Cr.

Then in 1 Mole of  $Cr_2O_3$ contains = 2 moles of Cr

Number of moles of Cr in 2.16 moles of  $Cr_2O_3=2\times 2.16 =4.32 moles$ of Cr.

There are 4.32 moles of Cr in 2.16 moles of  $Cr_2O_3$.