Why is a spectrum for a given element unique for that element? a. no element has more than two electrons in the first shell. b. each element has a unique arrangement of electrons. c. atoms of different elements have different masses. d. atomic nuclei contain no electrons.

Plz mark brainliest 30 points 1) find the momentum of a 12 kg snowball that is rolling with a velocity of 9 m/s. 2) an 8 ball with a mass of .5 kg is sitting at rest. it is hit by the cue ball (1 kg) traveling at 2.5 m/s. if the cue ball is at rest after the collision, how fast is the 8 ball traveling after the collision? 3) two football players are running toward each other. if the offensive player is 75 kg and is running 8 m/s, how fast must the 60 kg defensive player run in order for the two players to hit and stop?

Which symbol can be used to indicate the pressure at which a chemical reaction is carried out? 25°c 2 atm pa

40dm3 of gas at 760 torr are heated from 5°c to 50°c what is the new volume