In variable state, the rate of flow of heat is controlled by
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(d)In variable state $\frac{Q}{t} \propto K$ and $\frac{Q}{t} \propto \frac{1}{{\rho \,c}}$==> $\frac{Q}{t} \propto \frac{K}{{\rho \,c}}$
( $K$ = thermal conductivity, $\rho$ = density, $c$ = specific heat)
( $K$ = thermal conductivity, $\rho$ = density, $c$ = specific heat)
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