Chemistry Unit Quiz

An element is:

• Made up of two or more types of atoms chemically combined

• A pure substance made of one type of atom

• A mixture of compounds

• Always found as a solid

A mixture:

• Has fixed ratios of atoms

• Is always a liquid

• Contains substances not chemically combined

• Is always homogeneous

The symbol for sodium is:

• S

• So

• Na

• Sd

The chemical formula CO2 shows:

• 2 carbon atoms and 1 oxygen atom

• 1 carbon atom and 2 oxygen atoms

• 2 carbon atoms and 2 oxygen atoms

• A mixture of carbon and oxygen

Which best describes the Law of Conservation of Mass?

• Mass can be created in a chemical reaction

• Mass is destroyed in burning reactions

• Mass is lost as gas escapes

• Mass is neither created nor destroyed in a chemical reaction

Endothermic reactions:

• Release heat to surroundings

• Feel hot

• Absorb heat from surroundings

• Produce flames

Increasing the concentration of a reactant:

• Decreases reaction rate

• Has no effect

• Increases reaction rate

• Stops the reaction

Increasing the surface area of a solid reactant:

• Slows down the reaction

• Makes no difference

• Speeds up the reaction

• Prevents a reaction from occurring

A reaction that feels cold to touch is:

• Exothermic

• Endothermic

• Displacement

• Synthesis

The smallest unit of an element that retains its properties is a(n):

• Molecule

• Atom

• Ion

• Compound