When it says Carbon has 2 unpaired electrons, is referring to the fact that Carbon has an electron configuration of [He]2s22p2. Therefore Carbon has 2 unpaired electrons in the p sublevel.
It is spontaneous at 298 k.
Answer:
The question is incomplete. The mechanism is not included in your question. The attached file contains the mechanism and the proposed mechanism.
Explanation:
See the attached file for the structure.