Given the following formula 2 kcio3 -> 2 kci + 3 o2 how many moles of o2 can be produced by letting 12 moles of kcio3 react?

1st you need to find the mole ratio between KClO3 and O2.  To find that you need to take the coefficents of each of the compounds.  That gives a ratio of 2:3.

Now we find out how many each unit is:
2x = 12
x = 6

Now we multiply it by 3 to find the number of moles of O2
3(6) = 18 mol O2. 

It’s b. mass i searched it up