Answer:
Oil has the smaller heat capacity. The effectiveness of the heat exchanger is 0.80.
Explanation:
Part 1:
In order to know which fluid has the smaller heat capacity we need to consider the heat equation below:
Q = CΔT, where Q is the heat exchanged, C is the heat capacity and ΔT is the variation in temperature.
As the heat exchange is the same for both fluids, the smaller the temperature variation, the smaller the heat capacity.
Water: ΔT = 120 °F
Oil: ΔT = 80 °F
Therefore, oil is the fluid with the smallest heat capacity.
Part 2:
The effectiveness of a counter-flow heat exchanger is given by the equation bellow:

Th1: initial temperature of the hot fluid
Th2: final temperature of the hot
Tc1: initial temperature of the cold fluid

Question is incomplete, complete question is;
A 34.8 mL solution of
(aq) of an unknown concentration was titrated with 0.15 M of NaOH(aq).

If it takes 20.4 mL of NaOH(aq) to reach the equivalence point of the titration, what is the molarity of
? For your answer, only type in the numerical value with two significant figures. Do NOT include the unit.
Answer:
0.044 M is the molarity of
(aq).
Explanation:
The reaction taking place here is in between acid and base which means that it is a neutralization reaction .
To calculate the concentration of acid, we use the equation given by neutralization reaction:

where,
are the n-factor, molarity and volume of acid which is 
are the n-factor, molarity and volume of base which is NaOH.
We are given:

Putting values in above equation, we get:

0.044 M is the molarity of
(aq).
Remark
The short Answer is 6. That's why the ion has a charge of minus 2. Oxygen is doing it's best to have its outer ring have 8 electrons which is the number of outer electrons contained in the outer ring of the Noble Gas Neon.
Answer 6.