8th Grade Science Review 7 (Physical/Chemical Properties)

Which statement is true of mercury?

• It is the densest substance listed.
• Its density is less than the density of water.
• It is a solid at 20B°C and 1.0 atm.
  
• Option 4 (optional) It is the densest liquid listed in the chart.

A substance has a mass of 10 g and a volume of 10 cm3. Based on the chart above, what is the substance? (Hint: the density equation is
D = m/V.)

• mercury
• oxygen
• water
• helium

Lee exposed iron nails to oxygen gas and found that iron oxide formed. Which statement about the experiment is correct?

• This is a physical change.
  
• This is a chemical change.
• Iron and iron oxide have the same properties.
• Oxygen and iron have similar properties.

What is a common outcome of chemical changes?

• One or more substances become new substances with different chemical properties.
• One or more substances become new substances with the same chemical properties.
• One or more substances stay the same with the same properties.
• One or more substances stay the same with different properties.

Sara tested the characteristics of a substance. Which observation represents a physical change in the substance?

• It burns in the presence of oxygen.
  
• It melts at 100°C.
• It bubbles in water.
  
• It turns green when exposed to moisture.

Which is a chemical change?

• Clear water turns red after a dye is added.
• Ice melts
• Salt dissolves in water.
• Milk sours.

A spring scale measures in newtons. Which of the following does a spring scale measure?

• temperature
• weight
• liquid volume
• mass

An irregular object’s volume is determined by displacement of water, as shown above. What is the volume of the object?

• 15 mL
• 40 mL
• 55 mL
• 95 mL

Jonathan finds the mass of the submerged object shown above to be 13.07 g. What can you conclude about the measurement?

• The measurement cannot be used to determine density without also knowing the force of gravity.
• The measurement is accurate because the resulting density is 0.87 g/mL, a common density of irregular objects.
• The measurement can be used to determine density because the object is not completely submerged in the water.
• The measurement is likely inaccurate because the resulting density, 0.87 g/mL, is less than that of water, 1.0 g/mL, which means it would float.

Max drops one effervescent tablet into a beaker of water and places a second tablet on the lab table. He observes bubbles of gas form on the surface of the tablet. The bubbles rise and break on the surface of the water. After several minutes, no more bubbles form and no tablet is visible in the water. The tablet on the lab table is unchanged. What conclusion should Max draw from his observations?

• The solid tablet changes directly into a gas through a physical change.
• The tablet breaks down when exposed to light and forms a gas through a chemical change.
• The tablet causes dissolved gases in the water to be released through a physical change.
• The tablet interacts with water to form a gas through a chemical change.