Answer : 1. "50th"
Explanation :

Justice DY Chandrachud to Take Oath As New Chief Justice of IndiaSenior-most Supreme Court judge and Chief Justice of India-designate Dhananjaya Y Chandrachud is all set to become the 50th head of the Indian judiciary when President Draupadi Murmu administers the oath of office to him at Rashtrapati Bhawan. Justice Chandrachud, born on November 11, 1959, was elevated to the top court on May 13, 2016. He has been part of several Constitution benches and landmark verdicts of the top court including on matters relating to the Ayodhya land dispute, the right to privacy and adultery. Justice Chandrachud was also part of the benches which delivered path-breaking judgements on decriminalising same-sex relations after it partially struck down Section 377 of the IPC, the validity of the Aadhaar scheme and the Sabarimala issue. Supreme Court judges retire at the age of 65. Justice Chandrachud is the second most senior judge of the Supreme Court.