Check-In Review 1

A piece of metal is composed of atoms. Each atom in the metal contains 29 protons. How is the metal classified?

• as a compound
• as an element
• as a mixture
• as a solution

Why is calcium (Ca) in group 2, period 4 on the periodic table?

• Calcium, like all group 2 elements, is nonreactive and a gas at room temperature
• Calcium, like all period 4 elements, is nonreactive and a gas at room temperature.
• Calcium, like all group 2 elements, is reactive and a solid at room temperature.
• Calcium, like all period 4 elements, is reactive and a solid at room temperature.

A copper wire was cut into pieces and dropped into a test tube containing acid. Bubbles formed immediately, the liquid in the test tube turned green, and the pieces of wire were no longer visible. Which most likely happened to the pieces of copper wire?

• The copper wire was chemically changed when it was cut and placed in the acid.
• The copper wire was physically changed when it was cut and placed in the acid.
• The copper wire was physically changed when it was cut and chemically changed when it was placed in the acid.
• The copper wire was chemically changed when it was cut and physically changed when it was placed in the acid.

The balanced equation below represents a chemical reaction. FeS + 2HCl → FeCl2 + H2S According to the law of conservation of mass, how many hydrogen and chlorine atoms are required for this reaction?

• 1 hydrogen atom and 1 chlorine atom
• 1 hydrogen atom and 2 chlorine atoms
• 2 hydrogen atoms and 1 chlorine atom
• 2 hydrogen atoms and 2 chlorine atoms

To ensure renewable energy resources, government regulations require logging companies to replant trees after they clear-cut a forest. Why is clear-cutting still a concern for the environment?

• It destroys entire habitats.
• It usually kills all animal life.
• It can cause acid rain to form.
• It usually causes the extinction of most plant life.

What will most likely occur if communities around the world increase the amount of wood they burn for heat?

• CO2 in the atmosphere will increase.
• CO2 in the atmosphere will decrease.
• Dissolved oxygen in the water will increase
• Dissolved oxygen in the water will decrease

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 workbench. After a few seconds, the liquids separate into layers. How are the contents of the flask classified?

• as an element
• as a compound
• as a homogeneous mixture
• as a heterogeneous mixture

Which elements have similar chemical properties?

• Na, K, Mg
• B, Al, S
• N, O, F
• He, Ar, Kr

Which distinguishes chemical changes from physical changes?

• Physical changes are permanent, while chemical changes are temporary.
• Chemical changes produce new substances, while physical changes do not.
• Physical changes alter the properties of the substance, while chemical changes maintain the same properties.
• Chemical changes result in a change in mass, while physical changes do not.

Two reactants, X and Y, are combined and form a new substance with a mass of 375 g. The mass of reactant X is 300 g. What is the mass of reactant Y?

• 75 g, because the mass of the reactants equals the mass of the products
• 175 g, because mass is lost after the chemical reaction
• 675 g, because the mass of the reactants equals the mass of the products
• 975 g, because mass is gained after the chemical reaction