When the room temperature becomes equal to the dew point, the relative humidity of the room is

Two identical metal bars are heated in two different temperatures and allowed to cool in the same surroundings. Which one of the following figures correctly shows their cooling curves?

For an ideal gas, a cyclic process ABCA as shown in P-T diagram, when presented in P-V plot, would be

Temperature of a body $\theta$ is slightly more than the temperature of the surrounding $\theta_0$. Its rate of cooling $(R)$ versus temperature of the body $(\theta)$ is plotted. Its shape would be