If an electric heater is rated at $1000\,W$,then the time required to heat one litre of water from $20\,^{\circ}C$ to $60\,^{\circ}C$ is

$A$ metal block of mass $3.3 \ kg$ is heated to a temperature of $400^{\circ} C$ and then placed on a large ice block. The specific heat of the metal is $0.4 \ J \ g^{-1} \ K^{-1}$ and the latent heat of fusion of water is $330 \ J \ g^{-1}$. The maximum amount of ice that can melt is: (in $kg$)

Ice at $-20\,^{\circ}C$ is added to $50\,g$ of water at $40\,^{\circ}C.$ When the temperature of the mixture reaches $0\,^{\circ}C,$ it is found that $20\,g$ of ice is still unmelted. The amount of ice added to the water was close to ........$g$ (Specific heat of ice $= 2.1\,J/g/^{\circ}C,$ Specific heat of water $= 4.2\,J/g/^{\circ}C,$ Heat of fusion of water at $0\,^{\circ}C = 334\,J/g).$

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 $50,^{\circ}C$.

$80\, g$ of water at $30^{\circ}C$ is poured on a large block of ice at $0^{\circ}C$. The mass of ice that melts is ........ $g$.

$A$ small quantity of water of mass $m$ at temperature $\theta^{\circ} C$ is mixed with a large mass $M$ of ice which is at its melting point. If $s$ is the specific heat capacity of water and $L$ is the latent heat of fusion of ice,then the mass of ice melted is: