Which statement is not true for an electrochemical cell? Electrons must flow through a separate path from the reaction solutions.

The metals that form the electrodes must be identical.

Nonparticipating ions must flow to keep the electrons electrically neutral.

An oxidation-reduction reaction must occur.

Which statement describes evidence of a chemical reaction? a) ice melting eliminate b) water boiling c) lighting a match d) grape juice freezing

Nebulae are enormous clouds in outer space. they are made mostly of hydrogen gas, helium gas, and dust. some nebulae glow brightly, while others do not. the stars that people see are huge, bright balls of glowing gas. they are made mostly of hydrogen and helium. which statement correctly describes other ways in which nebulae and stars are different? a. stars can form inside a nebula but a nebula can never be produced by any star. b. a star always has a higher density than a nebula. c. stars can never form inside a nebula but a nebula can be produced by any star. d. a nebula always has a higher density than a star.

What is the approximate vapor pressure when the gas condenses at 70 degrees celsius