When the products of a reaction have a lower enthalpy than the reactants___?

1) the reaction is endothermic

2) the reaction is exothermic

3) the change in enthalpy is positive

4) the reactants lost internal energy

The reactión is exothermic

Explanation:

The change in enthalpy follow the next equation:

ΔH = ΔH (products) - ΔH (reactants)

If the products have a lower enthalpy means that ΔH<0; this mean that the reaction gives heat to the environment

2) The reaction is exothermic reaction.

Explanation:

An exothermic reaction: A chemical reaction in which the energy is released in the surrounding in the form of either heat or light. The temperature of products in the exothermic reaction is higher than the reactants. Also, the net change in enthalpy is negative.

The exothermic reaction is denoted by:

Reactants → Product + Energy

The net change in enthalpy is found by taking the difference in energy between the energy used to form product bonds and the energy used to break the reactant bond.

But the energy used to break reactant bond is greater than the energy used to break reactant bond so the net enthalpy in the reaction is negative.