Which of the following always changes when a substance undergoes a chemical change? A. State of matter of the substance.

B. Arrangement of the atoms composing the substance.

C. Color of the substance.

D. Mass of the substance.

A. State of matter of the substance.

Explanation:

During a chemical change, the composition of matter always changes.

I would say C.

Explanation:

My best bet is C but in all honesty, i have no clue. -hope my non-helping helped :D

(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