. Does a more negative heat of formation (a larger negative number) mean that a compound is more stable or less stable than an isomer with a less negative heat of formation

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Explanation:

Heat of formation, also called standard heat of formation, enthalpy of formation, or standard enthalpy of formation, the amount of heat absorbed or evolved when one mole of a compound is formed from its constituent elements, each substance being in its normal physical state (gas, liquid, or solid)(Encyclopedia Britannica).

The greater the magnitude of the negative value  of the heat of formation(the more negative), the greater stability of the compound formed. Hence, a more negative heat of formation (a larger negative number) means that a compound is more stable than an isomer with a less negative heat of formation.

the molecules move in straight line until they collide with each other or with the walls of the container. collisions are perfectly elastic; when two molecules collide, they change their directions and kinetic energies, but the total kinetic energy is conserved.

explanation:

a boiling water reactor does not boil the water. a pressurized water reactor boils the water faster. a pressurized water reactor is heated directly by the core. a pressurized water reactor does not use fission.