How many half-lives are required for the concentration of reactant to decrease to 3.125 % of its original value for a first-order reaction

Lewis structure and molecular geometry for nh2cl

Explain why pure hydrogen cyanide does not conduct electricity, but become a conductor when it is dissolved in water? (at room temp, pure hcn exists as a volatile liquid)

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.