Paraphrasing and summarizing
It’s blurry.... try again
The suffix -ene tells that there is a double bond present in the molecule, and the 2 tells where in the molecule the bond is located. The molecule looks like this:
CH3-CH=CH-CH3
-ane indicates single bonds
-ene indicates at least one double bond
-yne indicates at least one triple bond
Answer:
magnesium + oxygen Right arrow magnesium oxide
Since we're talking about a chain reaction, I think this would be a) self-sustaining. Chain reactions are not usually described as "weak" and can be highly explosive depending upon the compounds (think Uranium!).
The first (artificial) self-sustaining nuclear reaction is attributed to Enrico Fermi in 1942. Here's a bit of history:
http://www.atomicarchive.com/History/firstpile/firstpile_01.shtml