this is a question which was asked in JEE advanced 2013 . This is a multiple choice question. I am confident about options b) , c) and d) being right but I have a doubt in the correctness of option a).
As you may observe the graph is nearly linear in the region 0-100K , hence we may say that C(heat capacity) can be represented as' mT '(where m is slope and T is temperature ). We know that dQ=CdT (by definition of heat). Hence when we substitute for C we get dQ= mT dT , on integration we get a second degree term in T i.e option a) would be incorrect since it says Q varies linearly with T.
In all the solution/answers I have found for this problem they all mark option a) to be correct with the reasoning
Please tell me what mistake I am making in my reasoning or where I am going wrong .