Which of the following substances (along with its corresponding salt) would be best suited for generating a buffer solution with a pH below 7? a. CH3CO2H
b. C5H5N
c. HCl
d. None of the above

d. None of the above

Explanation:

A buffer works when pH of the buffer is ± 1. Out of this range, the buffering capacity is very low.

Acetic acid, CH₃CO₂H, has a pKa of 4.74. That means its buffering capacity is between 3.74 and 5.74 of pH. Is not a good buffer to pH 7

Pyridine is a weak base with pKa of 5.52. Its buffering capacity is between 6.52 and 4.52. Is not a good buffer to pH 7

HCl is a strong acid. Just weak acids and bases can produce a buffer with its conjugate base. HCl can't produce a buffer.

Thus, right answer is:

(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