A copper rod (initially at room temperature `20^(@)C`) of non-uniform cross section is placed between a steam chamber at `100^(@)C` and ice-water chamber at `0^(@)C`. `A` and `B` are cross sections are as shown in figure. Then match the statements in column -I with results in columns-II using comparing only between cross section `A` and `B`. (The mathematical expressions in column-I have usual meaning in heat transfer).

`{:(,"Column-I",,"Column-II"),((A),"initially rate of heat flow" ((dQ)/(dt))"will be ",(p),"Maximum at section" A),((B),"At steady state rate of heat flow" ((dQ)/(dt)) "will be ",(q),"Maximum at section" B),((C),"At steady state temperature gradient" |((dT)/(dx))| "will be " ,(r),"Minimum at section B"), ((D), "At steady state rate of change of temperature"((dT)/(dt)) " at a certain point will be",(s),"Same for all section"):}`

Explanation

Initially rate of heat flow will be maximum at `A` and minimum at `B` as there is no temperature difference across section `B`.
In steady state `(dQ)/(dt)` will be same.
In steady state `(dQ)/(dt) = -KA(dT)/(dx)`= same & `(dT)/(dt) = 0 implies ((dT)/(dx)) prop (1)/(A) implies ((dT)/(dx))`
will be maximum at `B` & minimum at `A`