Your son is under Venus-Mercury period from 18/12/2015 to 18/10/2018. Venus is placed in 5th house in Chalit but is combust while Mercury is retrograde and is placed in nakshatra of debilitated Saturn and has ketu as sublord.
Chances of him acing a competitive exam next year seems low but best way to answer such event specific questions is to leverage prashna/horary if query is genuine (go to a nearby astrologer).
He will start Sun Mahadasha period from 18/12/2019 and that period will be better for education and career (Saturn in 10th house, Mars as 10th lord in 3rd and Sun in 5th house show that technical field/engineering will be good for him)
Given his age, asking question about marriage doesn’t makes sense.