What must be true for any endothermic reaction?

Question

There must be a phase change from solid to liquid or from liquid to gas.
There are more products than there are reactants.
The chemical bonds of the products have more energy than the chemical bonds of the reactants.
The reaction must take place in a sealed container held at constant volume.

Answer 1

The chemical bonds of the reactants have more energy than the chemical bonds of the products.