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

hence option A is correct

Explanation:

heat required from -9°C to 0°C ice = mass × specific heat of ice ×change in temperature

heat required from -9°C to 0°C ice = 7×2100×9 =132300 J =0.1323 MJ

( HERE SPECIFIC HEAT OF ICE IS A CONSTANT VALUE OF 2100

J/(kg °C )

heat required from  0°C ice to 0°C water = mass× specific heat of fusion of ice

                                                             = 7×3.36×10^5

                                                              = 2.352 × 10^6 J

                                                              = 2.352 MJ

TOTAL HEAT ENERGY REQUIRED = 0.1323 MJ +2.352 MJ

                                                          = 2.4843 MJ

hence option A is correct

at positions a, g kinetic energy is maximum.

at position d, potential energy is maximum.