31. The mass number of a nucleus is : a) always less than its atomic number: b) the sum of the number of protons and neutrons present in
the nucleus; c) always more than the atomic weight; d) a fraction.

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?

What is the name of the molecular compound s3i9?

Which of the following is the best explanation why some reactions appear to stop before all the reactants are converted to products? the reaction goes to completion. the reaction reaches equilibrium and the products stop being formed. the reversible reaction occurs at the same rate. the limiting reactant prevents the forward reaction occurring.