How many energy levels does the element helium have? I appreciate the help!

Please try your best to answer this!

Iknow the answer to 13 is b and 14 is d. i just need to know why the correct answers are correct

In pea plants, the allele for tallness (t) is dominant to the allele for shortness (t). in the cross between a tall pea plant and a short pea plant shown below, what is the probability that the resulting offspring will be tall? whats the percent

Plz mark brainliest 30 points1) 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?