Which Reaction Would You Expect to Have the Smallest Energy $\Delta$

Multiple Choice

Which reaction would you expect to have the smallest energy of activation? $\Delta$ H°(kJ mol^-1)

A) CH₃· + CH₃· -- $\rightarrow$ CH₃CH₃ -378
B) CH₄ + F· -- $\rightarrow$ CH₃· + HF -130
C) CH₄ + I· -- $\rightarrow$ CH₃· + HI +142
D) CH₄ + Br· -- $\rightarrow$ CH₃· + HBr +104
E) CH₄ + Cl· -- $\rightarrow$ CH₃· + HCl +8