Question

the temperature of a thermometer decreases during a chemical reaction. what happens to the energy of the reaction (system)? the reaction releases energy (- or exothermic). .the reaction absorbs energy (+ or endothermic). the reaction does not cause an energy change.

Explanation:

In a chemical reaction, if the thermometer's temperature decreases, it means the surroundings (like the thermometer) are losing heat. The system (reaction) is absorbing heat from the surroundings, which is characteristic of an endothermic reaction (energy is absorbed, signified as + or endothermic). Exothermic reactions release energy, increasing the surroundings' temperature, so that's not the case here. And reactions do involve energy changes, so the third option is incorrect.

Answer:

. The reaction absorbs energy (+ or endothermic).