The coefficient of thermal conductivity of copper, mercury and glass are respectively `K_(c), K_(m)` and `K_(g)` that `K_(c) gt K_(m) gt K_(g)`. If the same quantity of heat is to flow per second per unit of each and corresponding temperature gradients are `X_(c), X_(m)` and `X_(g)`, then

Options

A. `X_(c)=X_(m) =X_(g)`
B. `X_(c) gt X_(m) gt X_(g)`
C. `X_(c) lt X_(m) lt X_(g)`
D. `X_(m) lt X_(c) lt X_(g)`

Answer

C

Explanation

We use `(dQ)/(dt) = -kA(dT)/(dx)`
`(dT)/(dx) prop (1)/(k)`
As `(dQ)/(dt) = `constant
` rArr X_(g) gt X_(m) gt X_(c)`