True or false the melting of ice cubes is a exothermic reaction

Endothermic Reaction are those reactions in which the reactants absorb the energy from their surrounding and forms the product.

Those changes in which a substance goes from More-ordered state to less-oredered state are endothermic. Where they change from less ordered to more ordered is exothermic.

More ordered means that the movement of vibration of the particles of the substance is less and the are more close to each other. More to less ordered state is given as,

Solid>Liquid>Gas.

In the question it asks about the melting of the ice cube. Ice cube is a solid, and when it will melt, it will change into the liquid water. As we know that, Solid is more ordered and Liquid is less ordered, and The change from more-ordered to less-ordered is endothermic thus the answer is ENDOTHERMIC.

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask