P.1.3 Review Questions

A scientist placed a sample of lithium into a container of water. The scientist observed the lithium floating and making a buzzing sound as gas bubbles were forming around it. Which conclusion is BEST supported by this observation?

• A chemical change took place

• The lithium was dissolved by the water

• Dissolved gasses were released

• Water was vaporized

A chemist observed bubbling and fizzing after adding an acid solution to a white powdery substance in a beaker. Which of the following can be inferred?

• The acid boiled when poured into the beaker.

• The acid and powder formed a new product.

• A physical reaction produced a gas mixture.

• A reaction occurred that produced heat.

As part of a study, a scientist observed a number of different molecular changes in matter. Which of the following observations provides evidence of a physical change?

• using heat to burn a log in a fireplace

• using light to produce sugar in plants

• a cake that was baked from many ingredients

• a bottle that was broken into many small pieces

A beaker contains a sample of water with a mass of 325 grams. The water in the beaker is boiled and weighed again after it cools. The new mass of the water is 305 grams. In this example of the conservation of matter in physical changes,

• the mass is less after it cools because water has less mass as a gas.

• the mass of the water was 305 grams and the mass of the water vapor was 20 grams.

• the process of boiling destroyed 20 grams of the water and left 305 grams of water.

• the heat energy created by boiling water makes up the rest of the mass.

A group of students observed the formation of bubbles when water boiled. What happened to matter because of the physical change to the water?

• New matter was created in the bubbles.

• Old matter was destroyed as the water turned to gas.

• Matter was conserved when it changed form.

• The composition of the matter changed.

Juan Carlos placed 35 grams of ice into a dry, 200-gram container. The top of the container was attached tightly. When the ice was completely melted, the student measured the mass of the container with the liquid water. What should the mass of the liquid water in the container be?

• 35 grams

• 165 grams

• 200 grams

• 235 grams

The drawing shows solid carbon dioxide changing into carbon dioxide gas. Which statement describes the relationship between the solid carbon dioxide and the carbon dioxide gas after all of the solid has changed to gas?

• They have the same volume

• The gas has less volume than the solid

• The gas has less mass than the solid

• They have the same mass

A science class is studying the states of matter. One group of students freezes 100 grams (g) of water in a cup. Another group of students melts 50 g of ice in a cup. Which of these will MOST likely occur at the end of the experiment?

• The temperature of both cups will be the same.

• Both samples in the cups will be in the same state.

• Both groups will have the same mass with which they started.

• The time required for the changes in states of matter will be the same.

When frozen carbon dioxide (CO₂) is heated, it changes directly into a gas. Which statement BEST indicates that a physical change has taken place?

• Heat caused an increase in gas production.

• Heat caused a new substance to form.

• Heat caused a decrease in energy.

• Heat caused a change in state.

Which task in the kitchen is an example of a physical change?

• frying an egg

• baking a cake

• toasting bread

• melting butter