Please sir can you explain the R,S configuration question of last year jee paper ???

The strategy for deciding the R-S arrangement of a compound with 2 chiral carbons is the same as deciding the R-S setup for a compound with just 1 chiral carbon. You dole out a need to the particles appended to every carbon in light of the sub-atomic weight and after that you see Prority 1 - 2 - 3 - 4 gatherings are orchestrated clockwise or hostile to clockwise. In the event that the gatherings are orchestrated in the clockwise course, then the arrangement is R and generally the setup is S. You do this for both the chiral carbons.