ACT Science : ACT Science

Study concepts, example questions & explanations for ACT Science

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Example Questions

Example Question #1 : How To Find Synthesis Of Data In Chemistry

Both gases and liquids are considered to be fluids that have individual molecules that move around with kinetic and potential energy. Kinetic energy, defined as the energy related to motion, takes three forms: translational energy that occurs as a molecule moves from position A to position B, rotational energy that occurs as a molecule spins around an imaginary axis at its center of mass, and vibrational energy that occurs as individual atoms in a molecular bond move towards and away from each other. Usually, molecules possess varying combinations of kinetic energy forms. In contrast, potential energy is defined as stored energy that could be released to become kinetic energy. The total energy of a molecule is fixed, meaning that a molecule has some combination of kinetic and potential energies.

 

Varying amount of kinetic and potential energies define how molecules in a fluid interact with each other. For example, when the kinetic energy of a molecule is high (greater than 1000J), it can no longer interact with neighboring molecules strongly enough to remain a liquid. However, if the potential energies are too high (greater than 1000 J), molecules cannot escape a liquid to become a gas. If the kinetic energy is high and the potential energy is low, molecules tend to become a gas and can be modeled by an equation known as the Ideal Gas Law:

 

 

 

Where P is the pressure of a gas, V is the volume, n is the number of moles of a gas, R is a constant, and T is temperature in degrees Kelvin.

 

The Ideal Gas Law perfectly applies to particles with no mass, no intermolecular interactions, and no true volume. However, real molecules do not adhere perfectly to the Ideal Gas Law.

At a constant temperature, the relationship between pressure and volume is best illustrated as:

Possible Answers:


Screen_shot_2014-03-08_at_7.58.58_am

Screen_shot_2014-03-08_at_7.59.08_am

Screen_shot_2014-03-08_at_7.59.03_am

Screen_shot_2014-03-08_at_7.59.13_am

Correct answer:


Screen_shot_2014-03-08_at_7.58.58_am

Explanation:

Using the provided formula, we see that at a fixed temperature, pressure is inversely proportional to volume. They are on the same side of the equals sign, but can better be equated by rearranging the equation as: . We can now see more clearly that pressure is inversly proportional to volume. This inverse relationship is depicted as a negative sloped linear curve.

Example Question #2 : How To Find Synthesis Of Data In Chemistry

Chemists can model how solids, liquids, and gases behave at different temperatures and pressures with a graph called a phase diagram. When the pressure and temperature are simultaneously known, a scientist can predict whether the material will be in a specific state. The diagram is divided into sections depending on the phase and the lines between sections represent phase transitions occurring between two or more separate phases.

 

In general, solids of neatly stacked molecules exist when temperatures are low and pressures are intermediate. These values decrease the kinetic energy of the molecules enough to allow for attractive forces to begin the stacking process. Liquids, by contrast, are found at intermediate pressures and temperatures. The temperature is high enough to impart enough kinetic energy to prevent solid formation and the pressure is high enough to prevent the liquid from becoming a gas. Finally, a gas forms at low pressures and high temperatures. The high level of kinetic energy prevents molecules from associating with one another.

 

Materials can undergo processes called phase transitions, meaning they can transition from one phase to another. The transition from a solid to a liquid is called melting, while the reverse transition is called freezing. Vaporization occurs when a liquid becomes a gas, while condensation occurs when a gas becomes a liquid. Finally, in a process called sublimation, a solid can directly become a gas without passing through a liquid phase. Additionally, when a gas directly becomes a solid, this is known as deposition. 

Act_ps

The process as a substance goes from its phase in area one to its new phase in area two is called __________.

Possible Answers:

Freezing

Melting

Vaporization

Condensation

Correct answer:

Melting

Explanation:

Paragraphs two and three in the passage help us answer this question. Using the information contained in paragraph two, we are able to determine that area one corresponds to the solid phase (low temperature and intermediate pressure) and area two corresponds to the liquid phase (intermediate pressures and temperatures). Thus, we are transitioning between the solid and liquid phases. According to paragraph three, this process is called melting. 

Example Question #791 : Act Science

Chemists can model how solids, liquids, and gases behave at different temperatures and pressures with a graph called a phase diagram. When the pressure and temperature are simultaneously known, a scientist can predict whether the material will be in a specific state. The diagram is divided into sections depending on the phase and the lines between sections represent phase transitions occurring between two or more separate phases.

 

In general, solids of neatly stacked molecules exist when temperatures are low and pressures are intermediate. These values decrease the kinetic energy of the molecules enough to allow for attractive forces to begin the stacking process. Liquids, by contrast, are found at intermediate pressures and temperatures. The temperature is high enough to impart enough kinetic energy to prevent solid formation and the pressure is high enough to prevent the liquid from becoming a gas. Finally, a gas forms at low pressures and high temperatures. The high level of kinetic energy prevents molecules from associating with one another.

 

Materials can undergo processes called phase transitions, meaning they can transition from one phase to another. The transition from a solid to a liquid is called melting, while the reverse transition is called freezing. Vaporization occurs when a liquid becomes a gas, while condensation occurs when a gas becomes a liquid. Finally, in a process called sublimation, a solid can directly become a gas without passing through a liquid phase. Additionally, when a gas directly becomes a solid, this is known as deposition. 

Act_ps

Which phase transition occurs as a material transitions from area two to area three in the figure?

Possible Answers:

Melting

Vaporization

Condensation

Freezing

Correct answer:

Vaporization

Explanation:

Using paragraph two, we can determine that area two corresponds to a liquid (intermediate temperatures and pressures) and area three corresoonds to a gas (high temperature and low pressure). According to paragraph three, this process is called vaporization. 

Example Question #111 : Chemistry

Chemists can model how solids, liquids, and gases behave at different temperatures and pressures with a graph called a phase diagram. When the pressure and temperature are simultaneously known, a scientist can predict whether the material will be in a specific state. The diagram is divided into sections depending on the phase and the lines between sections represent phase transitions occurring between two or more separate phases.

 

In general, solids of neatly stacked molecules exist when temperatures are low and pressures are intermediate. These values decrease the kinetic energy of the molecules enough to allow for attractive forces to begin the stacking process. Liquids, by contrast, are found at intermediate pressures and temperatures. The temperature is high enough to impart enough kinetic energy to prevent solid formation and the pressure is high enough to prevent the liquid from becoming a gas. Finally, a gas forms at low pressures and high temperatures. The high level of kinetic energy prevents molecules from associating with one another.

 

Materials can undergo processes called phase transitions, meaning they can transition from one phase to another. The transition from a solid to a liquid is called melting, while the reverse transition is called freezing. Vaporization occurs when a liquid becomes a gas, while condensation occurs when a gas becomes a liquid. Finally, in a process called sublimation, a solid can directly become a gas without passing through a liquid phase. Additionally, when a gas directly becomes a solid, this is known as deposition. 

Act_ps

The phase transition occuring at Point C where a substance moves from area one to area three is called __________.

Possible Answers:

Vaporization

Sublimation

Condensation

Deposition

Correct answer:

Sublimation

Explanation:

Paragraph three helps us understand that sublimation occurs when a substance transitions from the solid phase directly to the gaseous phase. Using the information also provided in paragraph two, we can see that area one is where the substance is in solid form (low temperature with intermediate pressure) and area three is where the substance is in gaseous form (high temperature and low pressure).

Example Question #112 : Chemistry

Chemists can model how solids, liquids, and gases behave at different temperatures and pressures with a graph called a phase diagram. When the pressure and temperature are simultaneously known, a scientist can predict whether the material will be in a specific state. The diagram is divided into sections depending on the phase and the lines between sections represent phase transitions occurring between two or more separate phases.

 

In general, solids of neatly stacked molecules exist when temperatures are low and pressures are intermediate. These values decrease the kinetic energy of the molecules enough to allow for attractive forces to begin the stacking process. Liquids, by contrast, are found at intermediate pressures and temperatures. The temperature is high enough to impart enough kinetic energy to prevent solid formation and the pressure is high enough to prevent the liquid from becoming a gas. Finally, a gas forms at low pressures and high temperatures. The high level of kinetic energy prevents molecules from associating with one another.

 

Materials can undergo processes called phase transitions, meaning they can transition from one phase to another. The transition from a solid to a liquid is called melting, while the reverse transition is called freezing. Vaporization occurs when a liquid becomes a gas, while condensation occurs when a gas becomes a liquid. Finally, in a process called sublimation, a solid can directly become a gas without passing through a liquid phase. Additionally, when a gas directly becomes a solid, this is known as deposition. 

Act_ps

The phase transition occuring at Point A where a substance goes from its phase in area two to its phase in area one is best described as __________.

Possible Answers:

Vaporization

Condensation

Boiling

Freezing

Correct answer:

Freezing

Explanation:

Paragraph three helps us understand that as a material transitions from a liquid to a solid, it is freezing. We can determine that area two is the liquid phase by noting that it is at intermediate pressure and temperature. Additionally, we can determine that area one is a solid by noting the low temperature and intermediate pressure. 

Example Question #113 : Chemistry

Chemists can model how solids, liquids, and gases behave at different temperatures and pressures with a graph called a phase diagram. When the pressure and temperature are simultaneously known, a scientist can predict whether the material will be in a specific state. The diagram is divided into sections depending on the phase and the lines between sections represent phase transitions occurring between two or more separate phases.

 

In general, solids of neatly stacked molecules exist when temperatures are low and pressures are intermediate. These values decrease the kinetic energy of the molecules enough to allow for attractive forces to begin the stacking process. Liquids, by contrast, are found at intermediate pressures and temperatures. The temperature is high enough to impart enough kinetic energy to prevent solid formation and the pressure is high enough to prevent the liquid from becoming a gas. Finally, a gas forms at low pressures and high temperatures. The high level of kinetic energy prevents molecules from associating with one another.

 

Materials can undergo processes called phase transitions, meaning they can transition from one phase to another. The transition from a solid to a liquid is called melting, while the reverse transition is called freezing. Vaporization occurs when a liquid becomes a gas, while condensation occurs when a gas becomes a liquid. Finally, in a process called sublimation, a solid can directly become a gas without passing through a liquid phase. Additionally, when a gas directly becomes a solid, this is known as deposition. 

Act_ps

At Point D, the material is most likley in what phase(s)?

Possible Answers:

Liquid

Gas

Solid

Solid, Liquid, and Gas

Correct answer:

Solid, Liquid, and Gas

Explanation:

The last sentence of the first paragraph gives us an indication of what Point D may represent. We are told that the lines between sections represents a phase transition occuring between those respective phases. At Point D, however, we see that all three phases intersect, implying that all phase transitions are occuring simulaneously at this point and thus all states of the material may be present. 

Example Question #114 : Chemistry

Chemists can model how solids, liquids, and gases behave at different temperatures and pressures with a graph called a phase diagram. When the pressure and temperature are simultaneously known, a scientist can predict whether the material will be in a specific state. The diagram is divided into sections depending on the phase and the lines between sections represent phase transitions occurring between two or more separate phases.

 

In general, solids of neatly stacked molecules exist when temperatures are low and pressures are intermediate. These values decrease the kinetic energy of the molecules enough to allow for attractive forces to begin the stacking process. Liquids, by contrast, are found at intermediate pressures and temperatures. The temperature is high enough to impart enough kinetic energy to prevent solid formation and the pressure is high enough to prevent the liquid from becoming a gas. Finally, a gas forms at low pressures and high temperatures. The high level of kinetic energy prevents molecules from associating with one another.

 

Materials can undergo processes called phase transitions, meaning they can transition from one phase to another. The transition from a solid to a liquid is called melting, while the reverse transition is called freezing. Vaporization occurs when a liquid becomes a gas, while condensation occurs when a gas becomes a liquid. Finally, in a process called sublimation, a solid can directly become a gas without passing through a liquid phase. Additionally, when a gas directly becomes a solid, this is known as deposition. 

Act_ps

Solid carbon dioxide is commonly stored in freezing cold, low pressure rooms to prevent loss of the material. If the temperature in the room slowly warmed, the solid carbon dioxide would most likely become what? 

Possible Answers:

Remain Solid

Cannot Be Determined

Gas

Liquid

Correct answer:

Gas

Explanation:

This question asks us to look at the figure to see what would happen if we keep the pressure constant but increase the temperature of the room storing the dry ice. We can see that as we move left to right across the figure, without changing pressure, that we cross the phase transition line for sublimation/deposition. Becasue the temperature is warming, we know we are going from a solid directly to a gas by the process of sublimation. 

Example Question #115 : Chemistry

Chemists can model how solids, liquids, and gases behave at different temperatures and pressures with a graph called a phase diagram. When the pressure and temperature are simultaneously known, a scientist can predict whether the material will be in a specific state. The diagram is divided into sections depending on the phase and the lines between sections represent phase transitions occurring between two or more separate phases.

 

In general, solids of neatly stacked molecules exist when temperatures are low and pressures are intermediate. These values decrease the kinetic energy of the molecules enough to allow for attractive forces to begin the stacking process. Liquids, by contrast, are found at intermediate pressures and temperatures. The temperature is high enough to impart enough kinetic energy to prevent solid formation and the pressure is high enough to prevent the liquid from becoming a gas. Finally, a gas forms at low pressures and high temperatures. The high level of kinetic energy prevents molecules from associating with one another.

 

Materials can undergo processes called phase transitions, meaning they can transition from one phase to another. The transition from a solid to a liquid is called melting, while the reverse transition is called freezing. Vaporization occurs when a liquid becomes a gas, while condensation occurs when a gas becomes a liquid. Finally, in a process called sublimation, a solid can directly become a gas without passing through a liquid phase. Additionally, when a gas directly becomes a solid, this is known as deposition. 

Act_ps

What property most likely allows for molecules to stack neatly when freezing?

Possible Answers:

Repulsive Forces

Increase in Potential Energy

Symmetric Molecules

Reduction in Kinetic Energy

Correct answer:

Reduction in Kinetic Energy

Explanation:

The beginning of paragraph two helps guide our thinking for this question. We know that molecules stack nearly when temperatures are low and pressures are intermediate. Decreasing kinetic energy allows the molecules to remain closer together and for the attractive forces that are present to initiate the stacking process. Thus, the beginning of the stacking process depends on the reduction in kinetic energy. 

Example Question #111 : Chemistry

The Ideal Gas Law is as follows:

 

 is pressure as measured in Pascals,  is volume as measured in cubic meters,  is the number of moles of the gas,  is the gas constant known as 8.314 Joules per mole times Kelvin, and  is the temperature measured in Kelvin.

A class of students began studying the Ideal Gas Law and how the Pressure and the Volume relate to one another. They took 20 moles of a sample gas and kept the room at a temperature of 300 Kelvin. They then used different sized containers of the gas to limit and expand the volume. At each different volume, they measure the pressure of the gas on its container. The table they made from their results is seen in table 1.

 

Temperature in Kelvin

Pressure Measured in Pascals

 

 

200 Kelvin

16, 628 Pascals

400 Kelvin

33, 256 Pascals

600 Kelvin

49, 884 Pascals

800 Kelvin

66, 512 Pascals

TABLE 1

 

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FIGURE 1

The graph the students made based on the data is seen in Figure 1.

Pressure is created by the movement of the gas molecules pushing against a container. 0 Kelvin is known as absolute 0, the temperature at which all molecule movement theoretically stops.

Will the pressure of a gas ever be  according to this graph?

Possible Answers:

Yes, but only if Kelvin is converted to Celsius since water freezes at 0 degrees Celsius.

Yes, but only if the theory holds true and the temperature reaches absolute 0 to stop all molecule movement.

No, because the plots on the graph do not support the theory of absolute zero.

No, because gas molecules' movement does not relate to temperature.

Yes, but only if the temperature in Kelvin gets so high that the molecules move fast enough to explode their container.

Correct answer:

Yes, but only if the theory holds true and the temperature reaches absolute 0 to stop all molecule movement.

Explanation:

The plots on the graph as well as the equation of the Ideal Gas Law do support the idea that when temperature is equal to zero, so is pressure.  

Example Question #112 : Chemistry

The Ideal Gas Law is as follows:

 is pressure as measured in Pascals,  is volume as measured in cubic meters,  is the number of moles of the gas,  is the gas constant known as 8.314 Joules per mole times Kelvin, and  is the temperature measured in Kelvin.

A class of students began studying the Ideal Gas Law and how the Pressure and the Volume relate to one another. They took 20 moles of a sample gas and kept the room at a temperature of 300 Kelvin. They then used different sized containers of the gas to limit and expand the volume. At each different volume, they measure the pressure of the gas on its container. The table they made from their results is seen in table 1.

 

Temperature in Kelvin

Pressure Measured in Pascals

 

 

200 Kelvin

16, 628 Pascals

400 Kelvin

33, 256 Pascals

600 Kelvin

49, 884 Pascals

800 Kelvin

66, 512 Pascals

TABLE 1

Img020

 

FIGURE 1

The graph the students made based on the data is seen in Figure 1.

Pressure is created by the movement of the gas molecules pushing against a container.  0 Kelvin is known as absolute 0, the temperature at which all molecule movement theoretically stops.

What would the pressure be if the temperature of the gas was increased to 273 Kelvin?

Possible Answers:

The answer cannot be determined from the equation

Correct answer:

Explanation:

The Ideal Gas Law is given with pressure measured in Pascals. If the number 273 Kelvin was plugged into the equation, the number of Pascals that would be .

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