The dimensions of the coefficient of thermal conductivity are
MLT−3K−1
For bar of cross-sectional area A,length (l) and having temperatures θ1 and θ2 at its two ends, the amount of heat energy Q flowing normally across the bar in time (t) is given byQ=KA(θ1−θ2)tl Where K is the coefficient of thermal conductivity . Therefore,K=QlA(θ1−θ2)t∴ of k=dimensions of Q×dimensions of ldimensions of A× of(θ1−θ2)×dimensions of t=ML2T−2×LL2×K×T=MLT−3K−1 Hence the correct choice is (d)