Question

Ozonolysis of propene followed by reduction with zinc and acetic acid

Answer 1

MECHANISM FOR REACTION OF ALKENE OZONOLYSISStep 1: 
The π electrons act as the nucleophile, attacking the ozone at the electrophilic terminal O. A second C-O is formed by the nucleophilic O attacking the other end of the C=C.Step 2: 
The cyclic species called the malozonide rearranges to the ozonide. Step 3: 
The ozonide decomposes on  work-up. Reductive work-up with (usually Zn / acetic acid) gives the two carbonyl groups.