How is a pure substance different from a mixture? a. pure substances cannot be separated by physical means. b. mixtures cannot be separated by physical means. c. a pure substance is heterogeneous. d. a mixture is made of one substance.

Which element forms an ionic bond with flourine? 1) fluorine 2) carbon 3) potassium 4) oxygen

Astable electron arrangement for an atom is one that does not easily change. how is this arrangement arrived at? a. valence electrons are transferred or shared to create a full outer shell of electrons. b. valence electrons are discarded into space to create a full outer shell of electrons. c. protons (positive charge) pair with valence electrons (negative charge) to create a strong bond. d. outer shells with valence electrons are transferred or shared.

What is the average rate of the reaction between 10 and 20 s?