What is a hypothesis a: a summary of the results of many experiments. b: a proposed explanation for what is observed. c: a well-tested explanation for many observations. d: an observation recorded from an experiment.

Silver tarnishes as silver metal reacts with hydrogen sulfide, h2s, in the air. in this reaction, dark silver sulfide, au2s, covers the surface of silver. when silver is polished, this coating of silver sulfide can be removed from the surface. this makes the silver shiny again. enter the coefficients that balance the tarnishing reaction equation. (type 1 for no coefficient.)

An object becomes electrically charged when: electrons are created in it electrons from it are destroyed electrons are transferred to it protons from it are destroyed protons are created in it

Acontrol during an experiment. might change remains constant does not exist does change