What is the Bronsted-Lowry definition of an acid?
a compound that donates protons
O a compound that accepts protons
O a substance that increases hydroxide ion concentration
O a substance that increases hydronium ion concentration

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.

To calculate percent by mass, use the equation below: calculate the percent by mass of each element. %n = % %h = % %o = %

Which activity describes an application of topographic maps? check all that apply. recreation, such as camping and hiking engineering, such as the construction of roads and buildings science, such as mapping stars in the sky business, such as analyzing population centers science, such as analyzing surface features