What element’s isotope do they use to predict temperatures of the past?
a. Hydrogen
b. Oxygen
c. Carbon
d. Nitrogen
*Pick one of these answers*

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?

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?

What is the value of the standard enthalpy of formation of an element in its most stable form?