Compare how is drums in headphones produced sounds of higher pitch and greater loudness

What produces wave a)sound b) heats c)transfer of energy d)vibrations

Hydrogenation reactions, in which h2 and an "unsaturated" organic compound combine, are used in the food, fuel, and polymer industries. in the simplest case, ethene (c2h4) and h2 form ethane (c2h6). if 140 kj is given off per mole of c2h4 reacting, how much heat (in mj) is released when 12 kg of c2h6 forms?

What is the most common reason for matter changing its state?