What would be the mass of 9.03 x 1021 molecules of hydrobromic acid (HBr)?

The wilson chamber is used to study: direction, speed, and distance of radioactivity the intensity of radiation the appearance of individual atoms all of the above

Me i dont know what to do! the table compares the number of electrons in two unknown neutral atoms. comparison of electrons atom number of electrons a 10 d 11 use this information to determine the number of valence electrons in the atoms. which of the following correctly compares the stability of the two atoms? both are unreactive. both are highly reactive. a is unreactive and d is reactive. a is reactive and d is unreactive.

How are isotopes of the same chemical element alike? how are they different?