I believe there has to be enough activation energy for a reaction to occur in the first place, if that is what you are referencing
Activation energy is what the type of energy is called
Hydrogen bonds exists between the DNA strand and its complementary strand such that; there are two hydrogen bonds between every A and T, and three between every C and G.
Therefore; in this case there will be (2 ×3 ) +(3×3) = 15 hydrogen bonds for the above strand. this is because Adenine binds to Thyamine with two bonds (3 pairs) and Guanine binds to Cytosine with three bonds (3 pairs).