7.6A Matter and Energy Spiral Review

Which of the following best describes the difference between elements and compounds?

• Elements contain only one type of atom, while compounds contain two or more different types of atoms bonded together
• Elements are always gases, while compounds are always solids
• Elements are always found in nature, while compounds are always synthetic
• Elements are always metals, while compounds are always non-metals

Using the periodic table, how many atoms of each element are in the chemical formula H₂O?

• One hydrogen atom and two oxygen atoms
• Two hydrogen atoms and one oxygen atom
• One hydrogen atom and one oxygen atom
• Three hydrogen atoms and one oxygen atom

Which change represents a chemical change?

• Ice melting into water
• Salt dissolving in water
• Iron rusting
• Sugar being ground into powder

In an aqueous solution, what is the solvent?

• The solid that dissolves
• The mixture of both substances
• Water
• The concentrated substance

What factor does NOT affect the rate of dissolution of a solid in water?

• Temperature of the solution
• Color of the solution
• Surface area of the solid
• Stirring the mixture

How can you identify a compound's chemical formula?

• By its color and smell
• By counting the number and types of atoms present
• By its physical state
• By its temperature

What happens when you increase the surface area of a solid solute?

• The solution becomes more dilute
• The temperature increases
• The rate of dissolution decreases
• The rate of dissolution increases

Which is an example of a physical change?

• Burning paper
• Milk turning sour
• Cutting paper into pieces
• Baking a cake

In a concentrated solution, what is true about the solute?

• There is less solute than in a dilute solution
• There is more solute compared to the amount of solvent
• The solute particles move faster
• The solute changes color

What happens to the rate of dissolution when you heat an aqueous solution?

• It stays the same
• It decreases slightly
• It increases
• It stops completely