HELP A scientist places a pH meter in a sample of concentrated potassium hydroxide (KOH). The scientist slowly adds nitric acid (HNO3) to the KOH and monitors the pH. Describe how the pH and hydronium ion concentration will change in the solution as the acid is added.

Neils bohr believed that electrons orbited the nucleus in different energy levels, based on strong support from

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

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.