Which Indian ministers have quit over moral reasons as Pradhan faces calls to resign?

Education Minister Dharmendra Pradhan is facing calls to resign over NEET paper leak. Lal Bahadur Shastri resigned as Railways Minister over moral reasons after the 1956 Ariyalur train accident, while VK Krishna Menon resigned as Defence Minister over 1962 Indo-China war. Shivraj Patil resigned as Home Minister and Vilasrao Deshmukh resigned as Maharashtra CM after 26/11 Mumbai terror attacks.