What alkene reacts the fastest with hbr?

Explanation:

The reaction with HBr is a nucleofilic adition with the following steps:

In the first step, the more sustituted the carbocation is the more stable. Meaning this that the most stable will be a terciary C (such as in ter buthene), the  less stable the primary C (ethene for example) and between them, the secondary C (propene).

Analizing that and knowing that this mechanism of reaction follows the rule of Markovnikov, you can determine the reaction speed of an alkene.

Also the more resonance intermediates it has, the slower the reacrion is.

no, the red giant is the hottest with 2.00.000.000 degrees celsius. while the white dwarf only 25,000 degrees celsius.

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).