8th Grade Chemistry Unit Test Review

What phase change occurs when water droplets form on a cold window from a student's breath?

• Freezing
• Condensation
• Boiling
• Evaporation

How do the properties of sodium chloride (NaCl) compare to those of sodium and chlorine?

• The same as those of sodium but not chlorine
• The same as those of chlorine but not sodium
• The same as both sodium and chlorine
• Different from those of sodium and chlorine

What best describes the combination of iron filings and sand?

• Solution
• Compound
• Heterogeneous Mixture
• Homogeneous Mixture

Which method would effectively separate iron filings from sand?

• Pour water into the mixture
• Use a magnifying glass
• Use a magnet
• Heat the mixture

Why is breaking a window considered a physical change?

• Energy is required to break the glass
• No new substances are created
• The mass of the glass is increased
• Sound energy is released

What does the recovery of sugar from a solution by evaporation demonstrate?

• Phase Change
• Physical Change
• Chemical Property
• Chemical Change

To dissolve more NH ₃ in a solution, what should you do?

• Heat the solution
• Cool the solution
• Keep the solution’s temperature the same

How many grams of KNO₃ will dissolve in 100 mL of water at 60°C? (Use the graph we colored)

• 30g
• 60g
• 90g
• 102g

What temperature is needed to dissolve 50 g of NH₃ ? (Use the graph we colored)

• 22°C
• 36°C
• 40°C
• 50°C

In which condition will sugar dissolve the fastest? (Powdered means we crushed up the sugar cube)

• Powder and cold water
• Powder and hot water
• Cube form and cold water
• Cube form and hot water