$250\,gm$ of water and an equal volume of alcohol of mass $200\,gm$ are placed successively in the same calorimeter and cools from $60^{\circ}\,C$ to $55^{\circ}\,C$ in $130\,sec$ and $67 sec$ respectively. If the water equivalent of the calorimeter is $10\,gm$. , then the specific heat of alcohol in cal/gm $cal / gm ^{\circ}\,C$ is
$1.30$
$0.67$
$0.62$
$0.985$
A water cooler of storage capacity $120$ litres can cool water at a constant rate of $P$ watts. In a closed circulation system (as shown schematically in the figure), tr e wat'r from the cooler is used to cool an external device that generates constantly $3 \mathrm{~kW}$ of heat (thermal load). The temperature of water fed into the device cannot exceed $30^{\circ} \mathrm{C}$ and the e.tire stored $120$ litres of water is initially cooled to $10^{\circ} \mathrm{C}$. The entire system is thermally insulat $\mathrm{d}$. The minimum value of $P$ (in watts) for which the device can be operated for $3$ hours is
(Specific heat of water is $4.2 \mathrm{~kJ}^{-1} \mathrm{~kg}^{-1}$ and the density of water is $10.$) $0 \mathrm{k}^2 \mathrm{~m}^{-3}$ )
$500\, g$ of water and $100\, g$ of ice at $0\,^oC$ are in a calorimeter whose water equivalent is $40\, g$. $10\, g$ of steam at $100\,^oC$ is added to it. Then water in the calorimeter is ....... $g$ (Latent heat of ice $\,= 80\, cal/g$, Latent heat of steam $\,= 540\, cal/ g$)
Heat given to a body which raises its temperature by $1\ ^oC$ is
Three liquids with masses ${m_1},\,{m_2},\,{m_3}$ are thoroughly mixed. If their specific heats are ${c_1},\,{c_2},\,{c_3}$ and their temperatures ${T_1},\,{T_2},\,{T_3}$ respectively, then the temperature of the mixture is
The water equivalent of $20 \,g$ of aluminium (specific heat $0.2 \,cal ^{-1}{ }^{\circ} C ^{-1}$ ), is ......... $g$