How to obtain Column Names having NAN values using PANDAS and store those column names in a List?

Question

I have a data frame as below,

df = pd.DataFrame({\'A\': [1, 2, 3, 4, 5],
              \'B\': [1, Nan, 2, 3, 4],
              \'C\': [2, 3, Nan, Nan,5],