The factor not needed to calculate heat lost or gained when there is no change of state is

Which of the following is the unit of specific heat?

The quantities of heat required to raise the temperatures of two copper spheres of radii $r_{1}$ and $r_{2}$ $(r_{1} = 1.5 r_{2})$ through $1 \ K$ are in the ratio of:

Heat energy at a constant rate is supplied to two substances $P$ and $Q$. If the variation of temperature $(T)$ of the substances with time $(t)$ is as shown in the figure,then select the correct statement.

Two substances $A$ and $B$ of the same mass are heated at a constant rate. The variation of temperature $\theta$ of the substances with time $t$ is shown in the figure. Choose the correct statement.

$A$ small electric heater is used to heat $200 \,g$ of water. The time required to bring all this water from $40^{\circ} C$ to $100^{\circ} C$ is $200 \,s$. If the specific heat of the water is $4200 \,J \,kg^{-1} \,K^{-1}$, then the power supplied by the heater is: (in $\,W$)