A closed system is:

completely closed to the outside environment.

only slightly exposed to the outside environment.

in constant exchange with the environment

completely exposed to the outside environment.

What is the main reason for processing coal ore? A) To increase heating value B) To remove inorganic material C) To eliminate pollution of groundwater D) To recover other valuable minerals from the ore

How do the atomic radius and metallic properties of sodium compare to the atomic radius and metallic properties of phosphorus? (1) Sodium has a larger atomic radius and is more metallic. (2) Sodium has a larger atomic radius and is less metallic.

What two things must be included in all measurements

What is the electron configuration of an element with atomic number 15?

I'm a chemical equation which symbol should be used to indicate that a substance is in solution

A molecule has one carbon-carbon double bond and four monovalent atoms or groups. how many different geometric isomers exist for this molecule?

While waiting for your car to warm up one winter morning, you notice a liquid dripping from your tailpipe. You recently learned in chemistry class that combustion reactions occur in car engines.

Which of the following correctly describes how metals behave in an ionic bond? Metals lose their valence electrons and form positive ions. Metals lose their valence electrons and form negative ions.

A pharmacist measures the mass of a powdered drug. The mass is 506 mg. What is the mass in grams? Write your answer as a decimal.

Which of these is a source of sediment? A. Fragments if other rocks B. Chemicals and minerals dissolved in water C. Sea shells D. All of the above