Grade 8_Topic 1-4 Review

The table shows the volume and mass of each liquid. When the student mixes all four liquids into one beaker, each liquid separates into a different layer. The formula for density is density = mass/volume. Which of the following lists the layers of the liquids in the beaker from the top to the bottom?

• corn syrup, dish soap, water, vegetable oil

• corn syrup, water, dish soap, vegetable oil

• vegetable oil, water, dish soap, corn syrup

• vegetable oil, dish soap, water, corn syrup

Tags

NGSS.MS-PS1-2

A student is given a sample of an unknown solid and asked to identify it. The student begins by making a list of questions to investigate about the sample. Which question would be the least useful in helping the student identify the sample?

• Is the sample soluble in water?

• What is the weight of the sample?

• Is the sample attracted to a magnet?

• What is the melting point of the sample

Several groups of students were given a 2-gram (g) cube of iron and a 4g cube of iron. They examined three physical properties of each cube: density, magnetism, and electrical conductivity. Which statement describes the most likely findings of the students?

• The cubes had identical properties because the amount of matter would not change these physical properties.

• The 2g cube had smaller values for the physical properties because the matter was squeezed together in a smaller space.

• The density and ability to conduct electricity remained the same but was twice as magnetic because the cube was twice as large.

• The 4g cube had a greater density, was more magnetic, and was a stronger conductor of electricity because it occupied a larger space

A student measures the mass and volume of three different metal samples. The student's data are recorded in the table. Which list shows the metals in order from most dense to least dense?

• nickel, zinc, iron

• nickel, iron, zinc

• zinc, iron, nickel

• zinc, nickel, iron

Tags

NGSS.MS-PS1-2

A student measures the mass of a beaker containing water to be 250 grams (g). She adds table salt to the beaker and stirs until all of the salt is dissolved and the solution is clear. How does the addition of salt affect the mass of the beaker and its contents?

• The mass of the beaker and its contents is still 250 g.

• The mass of the beaker and its contents is now less than 250 g.

• The mass of the beaker and its contents is now greater than 250 g

• The mass of the beaker and its contents depends on whether new atoms are formed.

Tags

NGSS.MS-PS1-5

A student weighs and then heats a petri dish of potassium carbonate (K₂CO₃). When heated, solid potassium carbonate (K₂CO₃) breaks down into solid potassium oxide (K₂O) and carbon dioxide (CO₂) gas. The student notes that after heating, the mass of the solid decreases. How might a student explain the difference observed?

• Some of the mass left as a gas.

• The mass that was lost was converted to energy.

• Mass is not conserved in reactions that produce carbon dioxide.

• Some of the potassium carbonate evaporated when heated.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A student performs an investigation and titles her report: The Effect the Amount of Rain has on the Clarity of Well Water. What is the tested variable (independent variable) in this investigation?

• the well

• the date of rain

• the amount of rainfall

• the clarity of the well water

Lynn tested the effect of different types of cooking oil on the amount of time it takes for a drop of water to fall through a container of oil. He poured the same amount of canola oil, olive oil, and coconut oil each into three different clear containers. He had his partner start a stopwatch at the exact moment he placed a water drop onto the surface of each oil. He recorded the time it took for each water drop to fall through the oil and analyzed the data. Which variable must Lynn hold constant in order to test the effect of the different types of cooking oils on the amount of time it takes for a drop of water to fall through the oil?

• the color of the oil

• the type of cooking oil

• the size of the containers holding the oil

• the time for a water drop to fall through the oil

Tags

NGSS.MS-PS2-2

Acid reflux occurs when acid from a person's stomach escapes from the stomach and enters the esophagus, a flexible tube that leads into the stomach. Which substance would be best for neutralizing stomach acid?

• a substance with a pH of 1

• a substance with a pH of 5

• a substance with a pH of 7

• a substance with a pH of 9

Which property differentiates metalloids from metals and nonmetals?

• Metalloids are much shinier than nonmetals and metals.

• Metalloids can have properties of metals and nonmetals.

• Metalloids are more reactive than metals and nonmetals.

• Metalloids conduct less heat and electricity than nonmetals and metals.