According to the second order formula:
1/[At] = K t + 1/[Ao]
and when we have the K constant =0.0265 & we have t = 180 min & we have the initial concentration of A = 4.25 so by substitution:
1/[At] = 0.0265 X 180min + 1/4.25
1/[At] = 5
∴[At] = 1/5 = 0.2 m
I think it is correct......
Answer:

Explanation:
= First mass of water = 12 oz
= Second mass of water = 20 oz
= Temperature difference of the solution with respect to the first mass of water =
= Temperature difference of the solution with respect to the second mass of water = 
c = Specific heat of water
As heat gain and loss in the system is equal we have

The final temperature of the solution is
.
Properties of acids are turns blue litmus red. pH is below 7 , reacts with metals to give off hydrogen gas and they have a sour taste. So option B will be the answer.