$0.1 \,m^{3}$ of water at $80^{\circ} C$ is mixed with $0.3 \,m^{3}$ of water at $60^{\circ} C$. The final temperature of the mixture is (in $^{\circ} C$)

$A$ thermos flask contains $250 \ g$ of coffee at $90^{\circ} C$. To this $20 \ g$ of milk at $5^{\circ} C$ is added. After equilibrium is established, the temperature of the liquid is (Assume no heat loss to the thermos bottle. Take specific heat of coffee and milk as $1.00 \ cal/g^{\circ} C$) (in $^{\circ} C$)

$A$ 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 $= 0.1 \ cal/gm ^\circ C$)

$2 \ g$ of steam at $100 \ ^\circ C$ is passed into $40 \ g$ of water at $25 \ ^\circ C$. The final temperature of the mixture becomes $54.3 \ ^\circ C$. Find the latent heat of vaporization of steam in $cal/g$.

$A$ glass beaker contains $200 \,g$ of carbonated water initially at $20^{\circ} C$. How much ice should be added to obtain the final temperature of $0^{\circ} C$ with all ice melted, if the initial temperature of ice is $-10^{\circ} C$ (in $\,g$)? Neglect the heat capacity of the glass.
[Take, $C_{\text{water}} = 4190 \,J/kg^{\circ} C$, $C_{\text{ice}} = 2100 \,J/kg^{\circ} C$, $L_F = 3.34 \times 10^5 \,J/kg$]

$A$ $210 \,W$ heater is used to heat $100 \,g$ of water. The time required to raise the temperature of this water from $25^{\circ} C$ to $100^{\circ} C$ is (specific heat capacity of water $= 4200 \,J / kg \cdot ^{\circ} C$). (in $\,s$)