Question

The energy stored in water formed from ice is
A.Latent heat of fusion of ice
B.$80ca{l^{ - 1}}$
C.Latent heat of boiling
D.Latent heat of fusion of water

Answer 1

Hint: The energy stored in water is the energy absorbed when ice changes its phase to water. The answer can be explained on the basis of latent heat which says about the energy absorbed or released during a phase change at constant temperature.

Complete step by step answer:
When ice melts to water the energy is absorbed and is an endothermic process.
And this energy absorbed or released during a phase transition with a constant temperature is called latent heat. For the melting process, it is called Latent heat of fusion. So, when water is formed from ice energy absorbed is called latent heat fusion of ice.
Let’s check with each option,
Just now we discussed that energy absorbed when ice changes to water is called latent heat of fusion of ice, so this option is correct.
Latent heat of fusion of ice is $80cal/g$ or $334.4joule/g$ . But in this option, they gave $80ca{l^{ - 1}}$ in which the unit given is wrong so this option is not correct. if its unit was $cal/g$ then this option would have been correct.
Latent heat of boiling or vaporization is the energy absorbed when water changes to ice, but in question ice is changing to water. So, this option is not correct.
Latent heat of fusion of water is energy change while freezing at constant temperature, it is the same as $80cal/g$ which is stored in water, but there will be a negative sign to show that energy is released, so this option is also correct.
So, for this question, the correct options are A and D.

Additional information:
When melting or vaporization occurs energy is absorbed and is an endothermic process. But freezing and condensation is an exothermic process and it will release energy.
Latent heat can be found using the formula,
$Q = m \times L$
Where $\,Q\,$ is heat, $\,m\,$ is the mass and $\,L\,$ is latent heat
And also $Q = m \times c \times \Delta t$
Where $\,c\,$ is specific heat and $\Delta t\,$ is the change in temperature.


Note:
Note that while choosing the answer there is a chance to choose B option, but in that option the unit is wrong even the same quantity is mentioned. So, we should be careful enough to not get mistaken. Also, in Latent heat of fusion of water the negative sign in the quantity is just indicating that energy is releasing so the amount of energy stored will be the same in water.