If chemical reaction A requires 270 kJ/mol of activation energy and chemical reaction B requires 180 kJ/mol of activation energy, which chemical reaction will naturally occur first?

Reaction B.

Explanation:

Hello,

In this case, since the physical meaning of activation energy defines how fast or slow a chemical reaction starts being undergone, we can infer that the greater the activation energy the slower it begins as it needs more energy and the smaller the activation energy the faster it begins since it needs less energy to start.

In such a way, since reaction B has a lower activation energy, it will readily start over reaction A.

Best regards.

as in mitosis, dna replication occurs during interphase.   in meiosis, it occurs specifically in s phase of interphase 1.