In order to determine whether a chemical reaction is exothermic or endothermic, which of the following must be determined?
a. how energy flows
b. the number of products formed
c. the number of reactants used
d. how atoms are rearranged

A. How energy flows

Explanation:-

Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and for the reaction comes out to be negative.

Endothermic reactions are defined as the reactions in which energy of the product is greater than the energy of the reactants. The total energy is absorbed in the form of heat and for the reaction comes out to be positive.

Thus in order to determine whether a chemical reaction is exothermic or endothermic , heat energy flow must be determined.

it is very well related to a lot of things but with my limited knowledge i can confidently say that the answer is space.

the chart show the masses and velocities of two colliding objects that stick together after a collision.

according to the law of conservation of momentum, the momentum of the object after the collision is  

answer

1,500

kg • m/s.