Which of the following statements is true/correct

The graph. Shown in the adjacent diagram, represents the variation of temperature $(T)$ of two bodies, $x$ and $y$ having same surface area, with time $(t)$ due to the emission of radiation. Find the correct relation between the emissivity

A body takes $4$ minutes to cool from ${100^o}C$ to ${70^o}C$. To cool from ${70^o}C$ to ${40^o}C$ it will take …….. $\min.$ (room temperature is ${15^o}C$)

According to Newton’s law of cooling, the rate of cooling of a body is proportional to ${(\Delta \theta )^n}$, where $\Delta \theta $ is the difference of the temperature of the body and the surroundings, and n is equal to

A body cools from $80\,^{\circ} C$ to $50\,^{\circ} C$ in $5$ minutes. Calculate the time (in $min$) it takes to cool from $60\,^{\circ} C$ to $30\,^{\circ} C .$ The temperature of the surroundings is $20\,^{\circ} C$