Six lectures on 6 different subjects physics, chemistry, Biology, Algebra, Geometry and Astronomy have to be scheduled (one on each day) across 7 days starting Sunday and ending Saturday. The schedule has to be drawn out for the subjects such that i. One day has to be a holiday and it can be neither Sunday nor Saturday. ii. Geometry has to be scheduled immediately after Algebra. iii. Physics cannot start the series in the week and has to be done exactly 2 days before Astronomy. iv. Biology has to be scheduled for Thursday and cannot immediately follow physics. Q. What subject will start the series of lectures?