Which of the following compounds would you expect to be the most reactive? a. ethyne b. ethene c. methane d. ethane

  The   compound  that  would  be   most   reactive  is   Ethyne  (answer A)

     explanation

   Ethyne   is the  most    unsaturated  among the four  compounds  ( it  has a triple bond between  the two carbon atoms) .
The  triple  bond in ethyne   is made up  of 1  sigma  bond  and  2π   bond.The 2π  bond  are  weaker   and can  easily break   which  make  Ethyne  more  reactive than  Ethene, methane  and Ethane.

Most likely a is the answer - because  you generate   38 atp's but also consume an atp.   each atp gives approx. less than 4 kcal so probably a is the closest answer.