examples30

id: 17791

question: Which solution has a higher concentration of pink particles?

choice: (A) Solution B (B) Solution A (C) neither; their concentrations are the same

context: The diagram below is a model of two solutions. Each pink ball represents one particle of solute.

gold answer: A

wrong prediction:

Rationale:

0: A solution is made up of two or more substances that are completely mixed.
1: In a solution, solute particles are mixed into a solvent.
2: The solute cannot be separated from the solvent by a filter.
3: For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution.
4: In this case, the salt is the solute.
5: The water is the solvent.
6: The concentration of a solute in a solution is a measure of the ratio of solute to solvent.
7: Concentration can be described in terms of particles of solute per volume of solvent.
8: concentration = particles of solute / volume of solvent In Solution A and Solution B, the pink particles represent the solute.
9: To figure out which solution has a higher concentration of pink particles, look at both the number of pink particles and the volume of the solvent in each container.
10: Use the concentration formula to find the number of pink particles per milliliter.
11: Solution A has more pink particles per milliliter.
12: So, Solution A has a higher concentration of pink particles.
13: The answer is B.

id: 17805

question: Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

choice: (A) The strength of the magnetic force is the same in both pairs. (B) The magnetic force is weaker in Pair 1. (C) The magnetic force is weaker in Pair 2.

context: The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material.

gold answer: A

wrong prediction:

Rationale:

0: Magnets can pull or push on each other without touching.
1: When magnets attract, they pull together.
2: When magnets repel, they push apart.
3: These pulls and pushes between magnets are called magnetic forces.
4: The stronger the magnetic force between two magnets, the more strongly the magnets attract or repel each other.
5: You can change the strength of a magnetic force between two magnets by changing the distance between them.
6: The magnetic force is weaker when the magnets are farther apart.
7: Distance affects the strength of the magnetic force.
8: When magnets are farther apart, the magnetic force between them is weaker.
9: The magnets in Pair 2 are farther apart than the magnets in Pair 1.
10: So, the magnetic force is weaker in Pair 2 than in Pair 1.
11: The answer is C.

id: 17821

question: Compare the average kinetic energies of the particles in each sample. Which sample has the higher temperature?

choice: (A) neither; the samples have the same temperature (B) sample A (C) sample B

context: The diagrams below show two pure samples of gas in identical closed, rigid containers. Each colored ball represents one gas particle. Both samples have the same number of particles.

gold answer: A

wrong prediction:

Rationale:

0: The temperature of a substance depends on the average kinetic energy of the particles in the substance.
1: The higher the average kinetic energy of the particles, the higher the temperature of the substance.
2: The kinetic energy of a particle is determined by its mass and speed.
3: For a pure substance, the greater the mass of each particle in the substance and the higher the average speed of the particles, the higher their average kinetic energy.
4: Each particle in the two samples has the same mass, but the particles in sample A have a higher average speed than the particles in sample B.
5: So, the particles in sample A have a higher average kinetic energy than the particles in sample B.
6: Because the particles in sample A have the higher average kinetic energy, sample A must have the higher temperature.
7: The answer is B.

id: 17888

question: Complete the statement. Methane is ().

choice: (A) an elementary substance (B) a compound

context: Methane is the main component of natural gas, which is used in homes for heating and cooking. The chemical formula for methane is CH4.

gold answer: B

wrong prediction:

Rationale:

0: There are more than 100 different chemical elements, or types of atoms.
1: Chemical elements make up all of the substances around you.
2: A substance may be composed of one chemical element or multiple chemical elements.
3: Substances that are composed of only one chemical element are elementary substances.
4: Substances that are composed of multiple chemical elements bonded together are compounds.
5: Every chemical element is represented by its own atomic symbol.
6: An atomic symbol may consist of one capital letter, or it may consist of a capital letter followed by a lowercase letter.
7: For example, the atomic symbol for the chemical element fluorine is F, and the atomic symbol for the chemical element beryllium is Be.
8: The atomic symbol for each chemical element in a substance is shown in the substance's chemical formula.
9: An elementary substance is represented by a chemical formula that contains only one atomic symbol.
10: The atomic symbol in a chemical formula may be followed by a small number written lower than the symbol.
11: This number is called a subscript.
12: A subscript is included when the atoms in the elementary substance are bonded to form molecules.
13: The subscript shows how many atoms are in each molecule.
14: For example, the chemical formula for the elementary substance oxygen, O2, has a subscript of 2.
15: This subscript shows that the atomic symbol O represents two atoms.
16: The elementary substance O2 and the chemical element represented by the atomic symbol O are both named oxygen.
17: So, the formula tells you that each molecule of O2 contains two oxygen atoms.
18: A compound is represented by a chemical formula that contains multiple atomic symbols.
19: The chemical elements in a compound are bonded together in a fixed ratio.
20: This ratio is shown in a compound's chemical formula.
21: For example, in the compound beryllium fluoride, there is one beryllium atom for every two fluorine atoms.
22: So, the ratio of beryllium atoms to fluorine atoms is 1 to 2.
23: This ratio is shown in the chemical formula for beryllium fluoride, BeF2.
24: There is no subscript following the atomic symbol Be because that symbol represents one atom.
25: The subscript 2 follows the atomic symbol F to show that the symbol represents two atoms.
26: You can tell whether methane is an elementary substance or a compound by counting the number of atomic symbols in its chemical formula.
27: An atomic symbol consists of either one capital letter or a capital letter followed by one or two lowercase letters.
28: The chemical formula for methane, CH4, contains one atomic symbol: C for carbon.
29: So, the formula tells you that methane is composed of only one chemical element.
30: Since methane is composed of only one chemical element, methane is an elementary substance.
31: The answer is A.

id: 17997

question: Which of the following best describes a community on the Serengeti plains?

choice: (A) the grasses, the soil, and the soil nutrients (B) the Burchell's zebras, the northern black rhinoceros, and the white-bearded wildebeests (C) the umbrella acacia trees

context: Read the passage. Then answer the question below. On the Serengeti plains in eastern Africa, umbrella acacia trees are scattered among many species of grasses that grow together. The grasses grow well because the soil has a lot of nutrients. The plains are home to many species of herbivores, such as Burchell's zebras, northern black rhinoceros, and white-bearded wildebeests. One reason so many species of herbivores can live together is that each species prefers to eat a different kind of plant. Figure: white-bearded wildebeests on the Serengeti plains.

gold answer: B

wrong prediction:

Rationale:

0: In an environment, organisms interact with each other and with their nonliving surroundings.
1: To help describe these interactions, ecologists use specific terms for different types of groups.
2: A single organism is an individual.
3: Individuals of the same species that live in the same place are part of a population.
4: Multiple populations of different species that live in the same place are part of a community.
5: Together, communities of living organisms and the nonliving parts of their environment make up an ecosystem.
6: The answer is A.

id: 18004

question: Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

choice: (A) The magnetic force is stronger in Pair 2. (B) The magnetic force is stronger in Pair 1. (C) The strength of the magnetic force is the same in both pairs.

context: The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material.

gold answer: B

wrong prediction:

Rationale:

0: Magnets can pull or push on each other without touching.
1: When magnets attract, they pull together.
2: When magnets repel, they push apart.
3: These pulls and pushes between magnets are called magnetic forces.
4: The stronger the magnetic force between two magnets, the more strongly the magnets attract or repel each other.
5: You can change the strength of a magnetic force between two magnets by changing the distance between them.
6: The magnetic force is stronger when the magnets are closer together.
7: Distance affects the strength of the magnetic force.
8: When magnets are closer together, the magnetic force between them is stronger.
9: The magnets in Pair 2 are closer together than the magnets in Pair 1.
10: So, the magnetic force is stronger in Pair 2 than in Pair 1.
11: The answer is A.

id: 18038

question: Which property do these three objects have in common?

choice: (A) rough (B) fuzzy (C) sticky

context: Select the best answer.

gold answer: B

wrong prediction:

Rationale:

0: An object has different properties.
1: A property of an object can tell you how it looks, feels, tastes, or smells.
2: Properties can also tell you how an object will behave when something happens to it.
3: Different objects can have properties in common.
4: You can use these properties to put objects into groups.
5: Look at each object.
6: For each object, decide if it has that property.
7: A rough object feels scratchy when you touch it.
8: None of the objects are rough.
9: A sticky object can attach or stick to other things.
10: All three objects are sticky.
11: A fuzzy object is covered in soft hair.
12: The wet glue and the tape are not fuzzy.
13: The property that all three objects have in common is sticky.
14: The answer is C.

id: 18058

question: Does this passage describe the weather or the climate?

choice: (A) weather (B) climate

context: Figure: Lake Bunyonyi. Lake Bunyonyi is located in the African country of Uganda. The wind speed on the lake averages about five miles per hour year-round. Hint: Weather is what the atmosphere is like at a certain place and time. Climate is the pattern of weather in a certain place.

gold answer: B

wrong prediction:

Rationale:

0: The atmosphere is the layer of air that surrounds Earth.
1: Both weather and climate tell you about the atmosphere.
2: Weather is what the atmosphere is like at a certain place and time.
3: Weather can change quickly.
4: For example, the temperature outside your house might get higher throughout the day.
5: Climate is the pattern of weather in a certain place.
6: For example, summer temperatures in New York are usually higher than winter temperatures.
7: Read the passage carefully.
8: Lake Bunyonyi is located in the African country of Uganda.
9: The wind speed on the lake averages about five miles per hour year-round.
10: The underlined part of the passage tells you about the usual wind speed on Lake Bunyonyi.
11: This passage describes the atmosphere at a certain place and time.
12: So, this passage describes the weather.
13: The answer is A.

id: 18190

question: Select the temperature shown by this thermometer.

choice: (A) 70°F (B) 35°F (C) 50°F

gold answer: C

wrong prediction:

Rationale:

0: A thermometer is a tool that measures temperature.
1: Temperature can be measured in degrees.
2: The symbol for degrees is °.
3: Some thermometers measure temperature in degrees Fahrenheit (°F).
4: Fahrenheit is one scale used to measure temperature.
5: This is a tube thermometer.
6: It has a tube filled with a red liquid.
7: There is a Fahrenheit scale along the right side of the tube.
8: The top of the red liquid lines up with the number 80 on the scale.
9: So, the temperature shown by this thermometer is 80°F.
10: Find the top of the red liquid.
11: Now look at the scale to the right.
12: The top of the red liquid is halfway between 70 and 80.
13: So, the temperature is 70°F.
14: The answer is A.

id: 18208

question: Which solution has a higher concentration of green particles?

choice: (A) Solution A (B) Solution B (C) neither; their concentrations are the same

context: The diagram below is a model of two solutions. Each green ball represents one particle of solute.

gold answer: B

wrong prediction:

Rationale:

0: A solution is made up of two or more substances that are completely mixed.
1: In a solution, solute particles are mixed into a solvent.
2: The solute cannot be separated from the solvent by a filter.
3: For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution.
4: In this case, the salt is the solute.
5: The water is the solvent.
6: The concentration of a solute in a solution is a measure of the ratio of solute to solvent.
7: Concentration can be described in terms of particles of solute per volume of solvent.
8: concentration = particles of solute / volume of solvent In Solution A and Solution B, the green particles represent the solute.
9: To figure out which solution has a higher concentration of green particles, look at both the number of green particles and the volume of the solvent in each container.
10: Use the concentration formula to find the number of green particles per milliliter.
11: Solution A has more green particles per milliliter.
12: So, Solution A has a higher concentration of green particles.
13: The answer is A.