Chemistry- Energy

Which distinguishes chemical changes from physical changes?

• Physical changes alter the properties of the substance while chemical changes maintain the same properties

• Physical changes are permanent while chemical changes are temporary

• Chemical changes produce new substances while physical changes do not

• Chemical changes result in a change in mass, while physical changes do not

Which statement best explains how periods on the periodic table are organized?

• increasing number of neutrons from left to right

• increasing atomic number from left to right

• decreasing number of electrons from left to right

• decreasing atomic mass number from left to right

Which is the best example of a pure substance?

• Saltwater

• Aluminum

• Air

• Sand

A scientist pours two liquids into a flask and swirls the flask to combine the liquids. The scientist then places the flask on a laboratory bench. After a few seconds the liquids separate into layers. How are the contents of the flask classified?

• Element

• Compound

• Homogeneous mixture

• Heterogeneous Mixture

Elements on the Periodic Table are arranged according to which characteristic?

• density

• atomic mass

• melting point

• atomic number

Which group on the Periodic Table is most reactive?

• Group 1

• Group 16

• Group 17

• Group 18

Why are Beryllium (Be), Magnesium (Mg), and Barium (Ba) in the same group?

• They have similar melting points

• They have are all in the same state of matter at room temperature

• Elements in the same group will chemically react with and identical element

• They have similar physical and chemical properties

Which best explains why the total mass of the

product(s) would be less than the total weight of the reactant(s) after a chemical reaction?

• A physical change occurred

• Atoms involved in the reaction lost mass.

• Precipitates were created in the new solution.

• Gases were released to the atmosphere.

How does a balanced chemical equation satisfy the Law of Conservation of Mass?

• During a chemical reaction, the total amount of matter stays the same.

• During a chemical reaction, matter is destroyed.

• During a chemical reaction, one or more new substances are formed.

• During a chemical reaction, the total number of atoms increases.

Which is the simplest form of matter?

• element

• mixture

• solution

• compound