Your answer, "7th", is not correct.
The correct answer to
On which day of the fifth month of the nineteenth year of Nebuchadrezzar, did Nebuzaradan, captain of the guard, come?
is
10th
as shown by
Jeremiah 52:12
which is
- KJV
- Now in the fifth month, in the tenth day of the month, which was the nineteenth year of Nebuchadrezzar king of Babylon, came Nebuzaradan, captain of the guard, which served the king of Babylon, into Jerusalem,
- NIV
- On the tenth day of the fifth month, in the nineteenth year of Nebuchadnezzar king of Babylon, Nebuzaradan commander of the imperial guard, who served the king of Babylon, came to Jerusalem.