Sickle-cell anemia is caused by: Group of answer choices a substitution of a serine residue for a glutamic acid residue at the beta-6 position a substitution of glutamic acid residue for histidine at the C terminus of the alpha chain a substitution of a glutamic acid residue for a phenylalanine residue at the beta-6 position a decreased production of alpha chains of hemoglobin polymerization of hemoglobin

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?