Under what circumstances will a scientific theory be changed or discarded

How do atoms usually combine? In a way that makes each atom less stable. In a way that makes each atom more stable. In a way that increases the number of valence electrons. In a way that decreases the number of valence electrons.

Select all the items that are related to compounds. 1. chemical bonding 2. physical change 3. maintain original physical properties 4. new physical properties 5. mixture of 2 or more elements

Classify the following compounds as ionic or covalent: a. MgCl2 b. Na2S c. H2O d. H2S

Identify each of the following solids as molecular, ionic, or atomic. Part A Br2 (s) molecular atomic ionic Part B AgCl (s) molecular ionic atomic Part C S (s) molecular ionic atomic Part D CH4 (s) atomic ionic molecular

How many grams of potassium chlorate are needed to create 11.2 liters of oxygen gas at stp?

To determine if a reaction is exoteric a student should use

Which of the following are physical properties of a penny? Choose all that are correct. Select one or more:a. Slightly red in color. b. Conducts electricity very well. c. Reacts to oxygen when heated. d. Resists corrosion from most acids.

NO2 and N2O4 undergo the reaction shown. When a sealed container of NO2 reaches chemical equilibrium, which must be true? A) No N2O4 is present. B) No chemical reactions are occurring. C) The rates of the forward and reverse reactions are equal.

What differences did you notice in the different states of water

1. Bubbling or fizzing is an indicator of a. property change b. phase change c. physical change d. chemical change