Which evidence is an indication that a chemical reaction has occured

How many moles of magnesium is 3.01 x10^22 atoms of magnesium?

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?

In an experiment, 45g of silicon tetrachloride are treated with 45ml of water. what is the theoretical yield in grams of hcl