Ca(No3)2 ------> Ca + NO2 + 2O2As you see from 1 mole of Ca(NO3)2 you get 1 mole of Ca 1 mole of NO2 and 2 moles of Oxygen. But 1 ,mole of Ca(NO3)2 weights 164.1 g"r and you have only 88.2 g"r that means you have 88.2/164.1 = 0.537 of a mole. And that will give you 1.075 moles (simply double) of Oxygen. Each mole (of any material) contains 6.023*10^23 atomes (or molecules) so you'll have: 1.075 * 6.023*10^23 = 6.475 * 10^23 atoms of Oxygen. Please note: My answer is different from John MvCann's answer. I believe that my answer is correct.
Your answer is incorrect. The molecule, Ca(NO3)2, is all that is in question here, not the productive equation. Thus the molar ratio I have indicated is the correct procedure for this problem.
There is not even intimation of an equation in this question.