Answer: If the theoretical yield is 2.35g then the percent yield is 80.4%
Explanation:
Given: Actual yield = 1.89 g
Theoretical yield = 2.35 g
Formula used to calculate the percentage yield is as follows.

Substitute the values into above formula as follows.

Thus, we can conclude that if the theoretical yield is 2.35g then the percent yield is 80.4%
Answer: B. Ca2+ + 2e- ---------> Ca
Explanation:
Reduction involves the gaining of electrons as well as a decrease in the oxidation state of the atom or ion.
In this case; Ca2+ gains two electrons and the oxidation state is reduced from +2 to 0.
Ca2+ + 2e- ---------> Ca
40 g Ar.......6.023*10^23 atoms
x g Ar.......3.8*10^24 atoms
x=40*3.8*10^24/(6.023*10^23)=252,365g Ar
I don't think that the whole question is posted here, but if you are looking for a way to balance this equation, I may have the answer. I believe the balanced equation is C5H8+9O2=4H2O+5CO2. If you need the reaction type, the answer is combustion. Hope this helps you.