13. Resistor: Substances that allow SOME electrons, but not all, to flow, which is measured in . These substances slow down the current to run light bulbs, appliances, engines, etc.

answer: c.

explanation:

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.

i believe the answer is three water molecules