Scientific Method and Density

Seawater is typically denser than freshwater due to seawater’s —

• higher salinity
• lower freezing point
• smaller mass
• greater depth

A student hypothesizes that water from infrequently used school faucets contains more chemical impurities than the water from frequently used faucets. At the same time of day, the student uses a water test kit to measure the water impurities from the different faucets. Which is the manipulated variable in this investigation?

• The chemicals used to test the water
• The amount of water per sample
• The time of day when water is collected
• The locations of water collection

At which range of altitude is air pressure closest to 40 kPa based on these data?

• Between 4.5 km and 6.0 km
• Between 6.0 km and 7.5 km
• Between 7.5 km and 9.0 km
• Between 9.0 km and 10.5 km

Students made a hydrometer by sealing the end of a straw with wax and adding some sand until the hydrometer barely floated in fresh water. The diagram shows what the students observed when they used the hydrometer to test water from three different sites. Each water sample had the same temperature. Which of these explanations best fits these observations?

• Estuaries are less salty than fresh water.
• Oceans support more microbes than fresh water.
• Salt water is denser than fresh water.
• Ocean water can freeze at lower temperatures than fresh water.

Tags

NGSS.MS-PS1-2

A student hypothesizes that a sample of rock formed from ocean sediments. Which would best help the student support this hypothesis?

• a textbook about rock formation methods

• rock samples from several locations on Earth

• a model of the different crustal plate boundaries

• clam shells found within the rock sample

Tags

NGSS.MS-ESS2-3

A student measured the mass and volume of a cube. What is the density of the cube.

• 0.35 g/cm³

• 1.36 g.cm³

• 0.79 g/cm³

• 1.02 g/cm³

Joseph wants to know which brand of fish food will make his goldfish grow the largest. He has 15 goldfish in each of his three 10-gallon tanks. In tank #1 he fed his fish his usual fish food, GrowBig. In the tank #2 he fed the fish Goldfish Goodies fish food. In tank #3 he fed the fish Lets Eat fish food. All three tanks received 10 grams of food per day. After six weeks the goldfish who were fed GrowBig grow and average of 2cm. The fish that ate Goldfish Goodies grew 4cm. The fish that ate Lets Eat fish food grew 1.5cm. What should Joseph do to verify his results?

• Repeat the experiment in the exact same manner

• Increase the size of tanks

• Use different types of fish

• Feed the fish different amounts of food

Tags

NGSS.MS-LS1-5

NGSS.MS-LS1-7

NGSS.MS-LS2-1

A student claims that the full moon occurs about once a month. What process will verify the student's claim?

• Predicting

• Theorizing

• Hypothesizing

• Observing

Tags

NGSS.MS-ESS1-1

In an experiment, what is the factor being tested or changed on purpose?

• Dependent Variable

• Independent Variable

• Constant

• Experimental Error

A student needs to determine the density of an unknown rock sample by dropping the rock into a graduated cylinder containing water. The original volume in the graduated cylinder is 23 mL. The student drops the rock sample into the graduated cylinder and the new volume is determined to be 30 mL. What can be concluded from this data?

• The volume of the rock is 7 mililiters

• The length of the rock is 7 milimeters

• The weight of the rock is 7 grams

• The density of the rock is 7 ounces

Tags

NGSS.MS-PS1-2