Their Period number is common means their "Principal Quantum Numbers" are same
Hope this helps!
For the First answer, It would be "A"
The for the next one the answer is "C"
I hope this helps. :)
The answer to the question is A
Answer:
The change in internal energy of the system is -17746.78 J
Explanation:
Given that,
Pressure 
Remove heat 
Radius = 0.272 m
Distance d = 0.163 m
We need to calculate the internal energy
Using thermodynamics first equation
...(I)
Where, dU = internal energy
Q = heat
W = work done
Put the value of W in equation (I)

Where, W = PdV
Put the value in the equation


Hence, The change in internal energy of the system is -17746.78 J