# If mass-­energy equivalence is taken into account, when water is cooled to form ice, the mass of water should Option 1) increase Option 2) remain unchanged Option 3) decrease Option 4) first increase then decrease.

As we learnt in

Kinetic energy -

$k= \frac{1}{2}mv^{2}$

- wherein

$m\rightarrow mass$

$v\rightarrow velocity$

kinetic Energy is never negative

Since water is cooled to form ice hence it must released energy. According to mass energy equivalence E = mc2

$\Delta m =\frac{\Delta E}{c^{2}}$

$\therefore \Delta E$ is negative and hence $\Delta m$ is also negative. so mass decreases. Correct option is 3

Option 1)

increase

This is an incorrect option.

Option 2)

remain unchanged

This is an incorrect option.

Option 3)

decrease

This is the correct option.

Option 4)

first increase then decrease.

This is an incorrect option.

N

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