Answer:
B. QC > 0; QH < 0
Explanation:
Given that there are two reservoir of energy.
Sign convention for heat and work :
1.If the heat is adding to the system then it is taken as positive and if heat is going out from the system then it is taken as negative.
2. If the work is done on the system then it is taken as negative and if the work is done by the system then it is taken as positive.
From hot reservoir heat is going out that is why it is taken as negative

From cold reservoir heat is coming inside the reservoir that is why it is taken as positive

That is why the answer will be
,
It can be a) 12Hz.................
Answer:
114.32195122 but Round your answer to three significant figures.) is 114
Explanation:
Just took the test
First of all, the formula for speed is;
Speed=distance/time
From the question, you have;
distance=7,200km
Time=9 hours
So that will be;
Speed=7200/9
When divided, you will have;
Speed=800
The unit for speed is km/hr or m/s. So that will be;
Speed=800km/hr
Hope that helped, have a nice day