When are reactions always spontaneous?
a) when the reaction is endothermic and the entropy is decreasing at a low temperature
b) when the reaction is exothermic and the entropy is increasing at a high temperature
c) when the reaction is endothermic and the entropy is increasing at a high temperature
d) when the reaction is exothermic and the entropy is decreasing at a low temperature

Calculate the h3o+ concentration in a solution of acetic acid if the concentration of molecular acetic acid present at equilibrium is 9.97x10^-3 m and k for the dissociation is 1.86x10^-5. ch3cooh(aq)+h2o(> h3o^+(aq)+ch3coo^-(aq)

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?

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation: