A reaction has an activation energy of 40 kJ and an overall energy change of –100 kJ. What is the activation energy, Ea, for the reverse reaction?

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.

Which property of water causes water drops to bead on a freshly waxed car?

What is the number of neutrons in an atom with atomic mass of 35