Which of the following is true for all chemical reactions? The total mass of the reactants increase. The total mass of the products is greater than the total mass of the reactants. The total mass of the products is less than the total mass of the reactants. The total mass of the reactants equals the total mass of the products.

The total mass of the reactants equals the total mass of the products.

Explanation:

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.

(newtons first law)

conservation of momentum law states :

momentum before collision = momentum after collision

momentum p (kg-m/s)= mass * velocity

say moving car=1 000 kg, velocity = 10 m/s then p = 1 000*10= 10 000 kg-m/s

say still car = 2 000 kg, velocity = 0 m/s then p = 2 000* 0 = 0 kg-m/s

total momentum prior to collision = 10 000 + 0 = 10 000 kg-m/s

momentum after collision = 10 000 kg-m/s

mass now = 1 000 kg+2 000 kg = 3 000 kg

10 000 = 3 000 kg* velocity m/s

10 000/3 000 = velocity

3.33 m/s = velocity after collision

an impulse is a force applied over time , momentum is exclusive of external forces and a perfect collision is implied