How many Molecules of oxygen are produced by the reaction of 7.89 grams of KCIO3 KCIO3 — KCI + O2

5.81×10²² molecules of oxygen.

Explanation:

This a reaction of decomposition:

2KClO₃ →  2KCl + 3O₂

2 moles of potassium chlorate can produce 2 moles of potassium chloride and 3 moles of oxygen.

We determine the amount of salt.

7.89 g. 1mol /122.55g = 0.0644 moles.

If 2 moles of salt, can produce 3 moles of oxygen.

0.0644 moles of salt may produce (0.0644 . 3) /2 = 0.0966 moles.

Let's count the molecules.

1 mol oxygen contains 6.02×10²³ molecules

Then, 0.0966 moles may contain (0.0966 . NA) = 5.81×10²² molecules

it is b that is the answer.

yes the answer is total mass in unchanged   : )