An ice cube is placed on a kitchen counter. which best describes heat flow in this situation

When an ice cube is placed on a kitchen counter, heat will flow from the ice cube to the counter, causing the molecules in the counter to move more slowly. The molecules of the counter move more slowly because the heat transferred to them from the ice has reduced their kinetic energy.

Then decomposition of water involves its breakdown into Hydrogen and Oxygen

The energy derived is absorbed which means it’s an endothermic reaction. If the energy is released to the surroundings/environment, it is termed as exothermic.

In an endothermic reactions, the reaction occurs when the bonds present in the reactants are broken and greater than the release of new bonds during products formation.