Question

2NaClO2---> 2NaCl + 3O2
if 3.85 grams of NaClO3 react, how many moles of O2 are created?

Answer 1

You have a typo somewhere. NaClO2 in the equation; NaClO3 in the problem.

mols NaClOx = grams/molar mass
Convert mols NaClOx to mols O2 using the coefficients in the balanced equation.