Matter and Energy Unit Review

What happens to the solubility of carbon dioxide gas in a carbonated drink when it is cooled?

• It increases.

• It decreases.

• It is not affected.

• It can increase or decrease.

Answer explanation

The solubility of carbon dioxide gas in a carbonated drink increases when cooled. This is due to the decreased kinetic energy of the gas molecules, allowing more CO2 to dissolve in the liquid.

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NGSS.MS-PS1-4

Which factor explains why a cube of sugar placed in water will dissolve at a slower rate than granular sugar over time?

• The mass of the cube decreases.

• The cube has a smaller surface area.

• The temperature of the cube decreases.

• The particles in the cube have more movement.

Answer explanation

The cube has a smaller surface area compared to granular sugar, which means fewer sugar particles are exposed to the water at once. This limits the rate at which the sugar can dissolve.

According to the graph, how much salt is expected to dissolve in 150 mL of water at 80°C?

• 30 grams

• 50 grams

• 70 grams

• 90 grams

Answer explanation

The graph indicates that at 80°C, 50 grams of salt can dissolve in 150 mL of water. Therefore, the correct answer is 50 grams.

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NGSS.MS-PS1-4

What question would BEST help understand why the volume of water changes when it turns from a liquid to a gas?

• A. How can the movement of the particles be described?

• B. Which model has the most gas molecules?

• C. Which model has the largest gas molecules?

• D. How can the temperature of the particles be described?

Answer explanation

Choice A is correct because understanding particle movement is key to grasping how water's volume changes during the transition from liquid to gas. It explains the behavior of particles in different states.

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A container of gas is held at a constant pressure. Which of these would cause the volume of the gas to decrease while the average kinetic energy of its molecules remains constant?

• increasing the number of gas molecules inside of the container

• decreasing the number of gas molecules inside of the container

• decreasing the Kelvin temperature of the gas

• increasing the Kelvin temperature of the gas

Answer explanation

Decreasing the number of gas molecules reduces the volume while keeping pressure constant. The average kinetic energy remains unchanged if the temperature is constant, as it is directly related to the number of molecules.

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Why can gases be compressed more easily than liquids?

• Because the particles in gases are closer together than in liquids.

• Because the particles in gases are farther apart than in liquids.

• Because gases have a fixed volume but liquids do not.

• Because gases have a definite shape but liquids do not.

Answer explanation

Gases can be compressed more easily than liquids because the particles in gases are farther apart. This greater distance allows gases to occupy less space when pressure is applied, unlike liquids, where particles are closer together.

A balloon is filled with helium and released. The pressure decreases as the balloon rises. Which will most likely happen to the balloon as it rises?

• The balloon will expand as it rises since the volume will increase.

• The balloon will shrink as it rises since the volume will decrease.

• The balloon will leak gas as it rises and the volume will decrease.

• The balloon will not change as it rises because the volume is constant.

Answer explanation

As the balloon rises, the external pressure decreases, allowing the helium inside to expand. This results in the balloon expanding as it rises since the volume will increase.

Which best describes energy changes in a system?

• A. Energy is conserved, but it can be created or destroyed.

• B. Energy is conserved, and it cannot be created or destroyed.

• C. Energy is not conserved, and it can be created or destroyed.

• D. Energy is not conserved, but it cannot be created or destroyed.

Answer explanation

Choice B is correct because it reflects the law of conservation of energy, which states that energy cannot be created or destroyed, only transformed. This principle is fundamental in physics.

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How many joules of energy are needed to warm 10.00 g of silver from 20.0°C to 25.0°C? (The specific heat of silver is 0.24 J/g°C.)

• 1.2 J

• 3.6 J

• 12.0 J

• 24.0 J

Answer explanation

To calculate the energy needed, use the formula Q = mcΔT. Here, m = 10.00 g, c = 0.24 J/g°C, and ΔT = 25.0°C - 20.0°C = 5.0°C. Thus, Q = 10.00 g * 0.24 J/g°C * 5.0°C = 12.0 J, which is the correct answer.

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NGSS.MS-PS1-4

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Which of the following statements about heat transfer is incorrect?

• Conduction occurs through direct contact of particles.

• Convection involves the movement of fluids.

• Radiation requires a medium to transfer heat.

• Heat transfer can occur through conduction, convection, and radiation.

Answer explanation

The incorrect statement is that radiation requires a medium to transfer heat. In fact, radiation can occur in a vacuum, unlike conduction and convection, which require a medium.

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