Create a dataframe of D1 and D2;

D1 = {‘Rollno’ : [1001, 1004, 1005, 1008, 1009], ‘Name’: [‘Sarika’, ‘Abhay’, ‘Mohit’, ‘Ruby’, ‘Govind’ ]}
D2 = {‘Rollno’ : [1002, 1003, 1004, 1005, 1006], ‘Name’:[‘Seema’,‘Jia’,‘Shweta’, ‘Sonia’, ‘Nishant’]}

(a) Concatenate row-wise.

(b) Concatenate column-wise.

The DataFrame D1 and D2 are created as :

import pandas as pd

Data1 = {'Rollno': [1001, 1004, 1005, 1008, 1009], 'Name': ['Sarika', 'Abhay', 'Mahit', 'Ruby', 'Govind']}
Data2 = {'Rollno': [1002, 1003, 1004, 1005, 1006], 'Name': ['Seema', 'Jia', 'Shweta', 'Sonia', 'Nishant']}

D1 = pd.DataFrame(Data1)
D2 = pd.DataFrame(Data2)
print(D1)
print(D2)

Output

   Rollno    Name
0    1001  Sarika
1    1004   Abhay
2    1005   Mahit
3    1008    Ruby
4    1009  Govind
   Rollno     Name
0    1002    Seema
1    1003      Jia
2    1004   Shweta
3    1005    Sonia
4    1006  Nishant

(a)

df = pd.concat([D1, D2])

Output

   Rollno     Name
0    1001   Sarika
1    1004    Abhay
2    1005    Mahit
3    1008     Ruby
4    1009   Govind
0    1002    Seema
1    1003      Jia
2    1004   Shweta
3    1005    Sonia
4    1006  Nishant

(b)

df = pd.concat([D1, D2], axis=1)

Output

   Rollno    Name  Rollno     Name
0    1001  Sarika    1002    Seema
1    1004   Abhay    1003      Jia
2    1005   Mahit    1004   Shweta
3    1008    Ruby    1005    Sonia
4    1009  Govind    1006  Nishant