According to Markovnikov's rule, where does H attach in addition reactions?

Markovnikov's rule states that in the addition of HX (where X is a halogen) to an alkene, the hydrogen atom (H) will attach to the carbon atom that already has the greater number of hydrogen atoms. This is based on the stability of the carbocation that forms during the reaction. When HX adds to an alkene, the intermediate carbocation is formed at the more substituted carbon, which is more stable due to greater hyperconjugation and inductive effects from surrounding alkyl groups.

Therefore, if we consider a symmetrical alkene with one carbon possessing two hydrogens and another carbon possessing one hydrogen, the addition will result in the hydrogen attaching to the carbon with the greater number of hydrogens. This results in the more stable intermediates and hence, follows the pathway predicted by Markovnikov's rule.

By adhering to this principle, the reaction favors the formation of products where the hydrogen is attached to the carbon with the most hydrogens initially, leading to a more stable and favorable reaction pathway.