Answer:
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Step-by-step explanation:
To find the number of moles of Cr(NO3)3 in the sample, we need to determine the number of moles of each element present in the compound.
The chemical formula for Cr(NO3)3 tells us that for every 1 mole of Cr(NO3)3, there is 1 mole of chromium (Cr), 3 moles of nitrogen (N), and 9 moles of oxygen (O).
We are given that the sample contains 8.36 moles of oxygen. Since the ratio of oxygen to Cr(NO3)3 is 9:1, the number of moles of Cr(NO3)3 in the sample is 8.36 moles O / 9 moles O/mole Cr(NO3)3 = 0.93 moles Cr(NO3)3.
Rounded to 3 significant figures, the answer is 0.93 moles Cr(NO3)3.