$A$ calorimeter of mass $0.2 \ kg$ and specific heat $900 \ J/kg \cdot K$ contains $0.5 \ kg$ of a liquid of specific heat $2400 \ J/kg \cdot K$. Its temperature falls from $60^{\circ}C$ to $55^{\circ}C$ in one minute. The rate of cooling is ....... $J/s$.

Statement $(I)$: $A$ device in which heat measurement can be made is called a calorimeter.
Statement $(II)$: Skating is possible on snow due to the formation of water below the skates. Water is formed due to the increase of temperature and ice melts.
Statement $(III)$: Two bodies at different temperatures are mixed in a calorimeter. The total internal energy of the two bodies remains conserved.
Which of the following is correct?

$A$ given mass $m$ of a hypothetical solid is supplied with heat continuously at a constant rate and the graph shown in the figure is plotted. If $L_f$ and $L_v$ are latent heats of fusion and vaporization,and $S_l$ and $S_s$ are specific heats of liquid and solid respectively,it can be concluded that:

The temperature of a body is given by $T = 6t^2 + 4$. The rate of change of temperature with respect to time at $t = 10 \ s$ is ........ $K/s$. ($T$ is in $Kelvin$ and $t$ is in $seconds$)

$A$ lead bullet of mass $50 \ g$ at a temperature of $30^{\circ}C$ is fired vertically upwards with a speed of $840 \ m/s$. When the bullet returns to the point of departure,it strikes a large block of ice at $0^{\circ}C$. How much ice (in $g$) will melt? (Specific heat of lead is $0.02 \ cal/g^{\circ}C$,latent heat of fusion of ice is $80 \ cal/g$,and assume all energy is used to melt the ice.)

The heat extracted out of $x \ \text{g}$ of water initially at $50^\circ \text{C}$ to cool it down to $0^\circ \text{C}$ is sufficient to evaporate $(1000 - x) \ \text{g}$ of water also initially at $50^\circ \text{C}$. The value of $x$ (closest integer) is . . . . . . . (Take latent heat of water $L = 2256 \ \text{kJ/kg}$, specific heat capacity of water $c = 4200 \ \text{J/kg}\cdot \text{K}$)