On what does the proportionality constant depends given in Newton's law of cooling.

Four spheres $A, B, C$ and $D$ are of same radius but made of different metals. Their densities are in ratio $6 : 3 : 4 : 5$ and specific heats are in ratio $2 : 5 : 4 : 6$ . These are initially kept at the same temperature and placed in the same surroundings. The sphere which has the slowest rate of cooling is

A body cools from $60^{\circ} C$ to $40^{\circ} C$ in $6$ minutes. If, temperature of surroundings is $10^{\circ} C$. Then, after the next 6 minutes, its temperature will be $.........{ }^{\circ} C$.

According to ‘Newton’s Law of cooling’, the rate of cooling of a body is proportional to the

Consider two hot bodies ${B_1}$ and ${B_2}$ which have temperatures ${100^o}C$ and ${80^o}C$ respectively at $t = 0$. The temperature of the surroundings is ${40^o}C$. The ratio of the respective rates of cooling ${R_1}$ and ${R_2}$ of these two bodies at $t = 0$ will be

Water and turpentine oil (specific heat less than that of water) are both heated to same temperature. Equal amounts of these placed in identical calorimeters are then left in air