How much heat energy (in megajoules) is needed to convert 7 kilograms of ice at –9°c to water at 0°c?

The heat  required to change the phase of a substance can be calculated by using the formula,

q = mCΔT where q is the heat needed, m is the mass of the substance, C is the specific heat capacity and ΔT is the change in temperature.

q = 7000 g (4.18 J/ g °C) (0°C - (-9°C))
q = 263340 J or .26334 MJ
Hope it's correct! ( If so rank as brainliest answer) :)

Attached below

Explanation:

The plot showing the potential as a function of distance from the center of the sphere is attached below

note : The Potential inside the sphere will remain constant as potential remains constant on surface and it start to decrease as 1/r