If a liquid takes $30 \; s$ in cooling from $80^{\circ} C$ to $70^{\circ} C$ and $70 \; s$ in cooling from $60^{\circ} C$ to $50^{\circ} C$,then find the room temperature. (in $^{\circ} C$)

$A$ liquid cools from $50^oC$ to $45^oC$ in $5$ minutes and from $45^oC$ to $41.5^oC$ in the next $5$ minutes. The temperature of the surrounding is ...... $^oC$.

Hot water kept in a beaker placed in a room cools from $70^{\circ}C$ to $60^{\circ}C$ in $4$ minutes. The time taken by it to cool from $69^{\circ}C$ to $59^{\circ}C$ will be

$A$ cup of tea cools from $80\,^{\circ}C$ to $60\,^{\circ}C$ in $1$ minute. The ambient temperature is $30\,^{\circ}C$. How long will it take to cool from $60\,^{\circ}C$ to $50\,^{\circ}C$?

Two circular discs $A$ and $B$ with equal radii are blackened. They are heated to the same temperature and are cooled under identical conditions. What inference do you draw from their cooling curves shown in the figure?

$A$ hot body,obeying Newton's law of cooling,is cooling down from its peak value $80\,^oC$ to an ambient temperature of $30\,^oC$. It takes $5\,minutes$ to cool down from $80\,^oC$ to $40\,^oC$. How many minutes will it take to cool down from $62\,^oC$ to $32\,^oC$? (Given $\ln 2 = 0.693, \ln 5 = 1.609$)