$A$ copper ball of mass $100 \ gm$ is at a temperature $T$. It is dropped into a copper calorimeter of mass $100 \ gm$,filled with $170 \ gm$ of water at room temperature. Subsequently,the temperature of the system is found to be $75 ^\circ C$. $T$ is given by......$^\circ C$ (Given: room temperature $= 30 ^\circ C$,specific heat of copper $= 0.1 \ cal/gm ^\circ C$)

$5 \ kg$ of water at $20^{\circ} C$ is added to $10 \ kg$ of water at $60^{\circ} C$. Neglecting the heat capacity of the vessel and other losses,the resultant temperature will be nearly: (in $^{\circ} C$)

Two tanks $A$ and $B$ contain water at $30,^{\circ}C$ and $80,^{\circ}C$ respectively. Calculate the amount of water that must be taken from each tank to prepare $40,kg$ of water at $50,^{\circ}C$.

$A$ coffee maker makes coffee by passing steam through a mixture of coffee powder,milk,and water. If the steam is mixed at the rate of $50 \, g/min$ in a mug containing $500 \, g$ of mixture,then it takes about $t_0$ seconds to make coffee at $70^{\circ} C$ when the initial temperature of the mixture is $25^{\circ} C$. The value of $t_0$ is close to .......... $s$ (ratio of latent heat of evaporation to specific heat of water is $540^{\circ} C$ and specific heat of the mixture can be taken to be the same as that of water).

Which of the following materials is used to make a calorimeter?

$A$ $2 \, kg$ block of ice at $-20^{\circ}C$ is added to $5 \, kg$ of water at $20^{\circ}C$. What will be the total mass of water in $kg$? (Specific heat of water = $1 \, kcal/kg/^{\circ}C$,specific heat of ice = $0.5 \, kcal/kg/^{\circ}C$,latent heat of fusion of ice = $80 \, kcal/kg$)