I believe the correct answer is sound waves. It is the sound waves that always need matter or a medium in order to propagate. Sound waves are mechanical waves that has different characteristics to electromagnetic waves which does not requires a medium to travel. Mechanical waves depend on the particles interaction for it to travel hence a medium is needed.
Answer from: Quest
your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.
Answer from: Quest
може ли да зареждате повече информация, моля
Another question on Chemistry
Chemistry, 22.06.2019 12:30
Acontrol during an experiment. might change remains constant does not exist does change
Lord kelvin described the concept of absolute zero temperature and the laws relating to the change of thermal energy during chemical reactions what type of chemist would he be considered today