# Can someone solve question iv? (its the top one)

Aug 11, 2018

Latent heat required to be removed along with the energy needed to be released to bring down the temperature to ${0}^{\circ}$

#### Explanation:

This happens because when the water at ${15}^{\circ} C$ came down to ${0}^{\circ} C$ it released some heat energy to get at that temperature.But to become completely same amount of ice at the same temperature, it will need its necessary latent heat to release....

This latent heat is required for the change in state of matter,because water at ${0}^{\circ} C$ has more amount of energy than ice at ${0}^{\circ} C$,which helps water molecule to float relatively free (weak cohesive force) w.r.t ice molecule.

So,on releasing that amount of energy,the kinetic energy of water molecule is reduced to such a state that they will get relatively stable and sit closer to make it a solid form i.e ice.

For, $1 g m$ of water this energy accounts for $80$ Calorie

That means $1 g m$ of ice at ${0}^{\circ} C$ has $80$ Calorie less energy that same amount of water at the same temperature,and this extra energy actually helped water molecule to overcome the attractive force of ice molecules to impart movability better say fluidity.

So,this amount of heat energy has to be released from the water which will require some time to cause the complete conversion.