Heat is flowing through a conductor of length l from $x = 0$ to $x = l$ . If its thermal resistance per unit length is uniform, which of the following graphs is correct

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 ${15^o}C$)

Draw the graph that represents the cooling of hot water with time. Is the slope of the above graph positive or negative ?

The rates of cooling of two different liquids put in exactly similar calorimeters and kept in identical surroundings are the same if

A calorimeter of mass $0.2$ kg and specific heat $900 J/kg-K$ . Containing $0.5$ kg of a liquid of specific heat $2400J /kg-K$ . Its temperature falls from ${60^o}C\,{\rm{to}}\,\,{\rm{5}}{{\rm{5}}^{\rm{o}}}C$ in one minute. The rate of cooling is ....... $J/s$

A container contains hot water at ${100^o}C$. If in time ${T_1}$ temperature falls to ${80^o}C$ and in time ${T_2}$ temperature falls to ${60^o}C$ from ${80^o}C$, then