Why do electrons occupy equal energy orbitals singly before beginning to pair up?

The term accuracy best refers to which of following

Apply Concepts Hard water contains calcium and magnesium ions. One way to soften water is to add sodium phosphate. Write complete and net ionic equations for the reaction of these two alkaline earth ions with aqueous sodium phosphate.

A student dissolves of potassium chloride in of water in a well-insulated open cup. He then observes the temperature of the water fall from to over the course of minutes.

What statement best describes nuclear binding energy?

Which statement best explains how atmospheric dust particles influence the water cycle? (1) Dust particles are the main source of dissolved salts in the sea. (2) Dust particles increase the capacity of the atmosphere to hold water vapor.

A substance that does not conduct electricity as a solid but does conduct electricity when melted is most likely classified as (1) an ionic compound (2) a molecular compound (3) a metal (4) a nonmetal

What is done with the reactive sodium after the reaction to make sure the products are safe in an air bag?

Which of the following does not indicate a chemical change? precipitate formation crushing a solid into a powder color change gas evolution

Reactions cannot occur without a certain minimum amount of energy. what is this minimum amount of energy called?

What are the products of the alpha decay of Iodine-131?