Which of the following alkenes reacts fastest with hbr

If a molecule with a molecular formula of c13h18 is treated with an excess of h2 in the presence of finally divided pt metal under conditions required for maximum hydrogenation of the molecule to give a molecule with a formula c13h24, how many rings are in the molecule?

In one or two grammatically correct sentences, write a definition for the term molecule geometry

Boron has an average atomic mass of 10.81. one isotope of boron has a mass of 10.012938 and a relative abundance of 19.80 percent . the other isotope has a relative abundance of 80.20 percent what is the mass of that isotope? report two decimal places