For which method of heat transfer can Newton's law of cooling be used?

$A$ body cools down from $75^{\circ}C$ to $60^{\circ}C$ in $10 \text{ minutes}$. It will cool down from $65^{\circ}C$ to $55^{\circ}C$ in a time:

$A$ body cools from $60^{\circ}C$ to $50^{\circ}C$ in $10$ minutes when kept in air at $30^{\circ}C$. In the next $10$ minutes,its temperature will be:

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?

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 $^{\circ} C$)

State Newton's law of cooling and derive its mathematical equation.