Question

How many ton of chlorine and propene is consumed to produce one ton of Allyl chloride ?

Answer 1

CH3CH=CH2 + Cl2 → ClCH2CH=CH2 + HCl
so, how many moles of C3H5Cl in a ton?
You'll use that many moles of each reactant
convert back to tons

Answer 2

Cl2 adds across the double bond and not as a substituent for a H atom. Most double bonds in organic chemistry work this way.
CH3CH=CH2 + Cl2 ==> CH3CH2CH3