Correct Answer - C

c) If T is the temperature of the interface of two plates of same area, then

`(dQ)/(dt) = (K_(1)A(10-7))/(Deltax_(1))=(K_(2)A(T-0))/(Deltax_(2))`

`(K_(1)A(10-T))/(Deltax_(1))=(3/2K_(1)A(T-0))/(3//2Deltax_(1))[thereforeK_(1)/K_(2)=2/3and (Deltax_(1))/(Deltax_(2))=2/3]`

or `10-T=T-0` or T+T = 10 or 2T = 10

`therefore` T = `5^(@)`C