C.
If 150 grams of oxygen are produced, how many moles of sodium chlorate decomposed

3.13 moles of sodium chlorate are decomposed.

Explanation:

Given data:

Mass of oxygen produced = 150 g

Number of moles of sodium chlorate decomposed = ?

Solution:

Chemical equation:

2NaClO₃   →   2NaCl + 3O₂

Number of moles of oxygen:

Number of moles = mass/molar mass

Number of moles = 150 g/ 32 g/mol

Number of moles = 4.7 mol

Now we will compare the moles of oxygen with sodium chlorate.

                     O₂           :           NaClO₃

                      3             :              2

                    4.7            :          2/3×4.7 = 3.13 mol

3.13 moles of sodium chlorate are decomposed.