N2(g) + 3H2(g) --> 2NH3(g); ΔH = -91.8 kJ Consider the thermochemical equation for the synthesis of ammonia. Which statement is true?

a. negative enthalpy indicates that energy is required to complete the reaction.

b. Negative enthalpy indicates a decrease in potential energy and an endothermic reaction.

c. Enthalpy is negative indicating that energy is released so this is an exothermic reaction.

d. Enthalpy is negative indicating that there is an energy deficit; the reaction is incomplete.

b. is the answer hoped i        

(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

i think tornado but not 100%