Answer
(a) greater than
(b) $139C^{\circ}$
Work Step by Step
(a) We know that the new temperature of the hot plate should be greater than $106C^{\circ}$ because there is an increase in the total heat flow when compared to the initial value and therefore in order to increase the heat flow, the temperature should be increased.
(b) We know that
$Q_{total}=(K_{cu}+K_{pb})A(\frac{\Delta T}{L})t$
We plug in the known values to obtain:
$25.2J=(395W/m.K+34.3W/m.K)(0.015m)^2(\frac{\Delta T}{0.525m})(1.0s)$
This simplifies to:
$\Delta T=137C^{\circ}$
$T_H-T_c=137C^{\circ}+2C^{\circ}=139C^{\circ}$
