Why would it be hard to find the ideal light intensity if the temperure were very hot or cold?

Light intensity is not dependent on temperature, with that said, plants (assuming that is what were talking about) would dehydrate faster at a higher temperature (unless they had mechanisms to cope e.g. C4 and CAM plants) with the same light intensity.

freezing

deposition

condensation

explanation;

melting also called fusion is the process where solid becomes liquid, sublimation is the process where solid becomes gaseous without first changing to liquid, deposition involves change from gaseous to solid state, freezing involves change from liquid to solid, boiling or evaporation involves change of liquid to gaseous state, while condensation is the change from gaseous state to liquid state.

endothermic reactions involves absorption of heat from the surroundings or the environment while exothermic reactions involves loss of heat energy to the surroundings.

in this case, sublimation, evaporation and melting are endothermic reactions (gain energy from the environment) while, freezing, deposition and condensation are exothermic (loss of energy to the surroundings) reactions.

close lines strong magnet less close weaker