Matter & Changes, Part 2 (8.P.9.1, 9.2, 9.3)

When plants and animals die, their bodies are decomposed by organisms such as bacteria or fungi. Which statement is true regarding the decomposition process?

• Decomposition is a physical change because the organism is broken down into new substances.

• Decomposition is a physical change because the identity of the dead plant or animal does not change.

• Decomposition is a chemical change because the identity of the dead plant or animal does not change.

• Decomposition is a chemical change because the organism is broken down into new substances.

Jenny takes a piece of paper and dips it in a bowl of water. The paper is now damp and mushy. Which of the following is/are true about the change that occurs when the paper gets wet?

I. It is a physical change

II. It makes a new substance

III. It is a chemical change

• II and III only

• I only

• II only

• I and II only

Sally's teacher tells her to find the masses of a sugar cube and a glass of water. Sally finds the masses to be 10 g for the sugar cube and 100 g for the glass of water. Then, the teacher tells her to put the sugar cube into the water. Sally puts the cube into the glass of water and watches as it dissolves. Then, the teacher tells Sally to estimate the new mass of the glass of sugar-water. What should Sally guess as the new mass of the glass of sugar-water?

• 200 g

• 110 g

• 90 g

• 50 g

A solution of salt water is boiled. The water evaporates and solid salt remains. Which statement is true?

• The salt has undergone a chemical change, and the water has undergone a physical change.

• The salt has undergone a physical change, and the water has undergone a chemical change.

• The salt and the water have both undergone chemical changes.

• The salt and the water have both undergone physical changes.

A substance is found to be reactive, flammable, soluble, and explosive. Which of these observations is a physical property?

• explosive

• soluble

• flammable

• reactive

Regan has an empty glass cup. It has a mass of 0.3 kg. She drops the cup on the ground and it shatters into several pieces. If she collected all of the pieces of the cup, how much mass would all of the pieces have combined?

• exactly 0.3 kg

• less than 0.3 kg

• There is no way to determine the mass of the shattered glass.

• more than 0.3 kg

Which of the following is an example of a chemical change?

• Flour and sugar are sifted together into a measuring cup.

• Chocolate squares are melted to make cake icing.

• A mixture of flour, sugar, eggs, and butter is baked to become a cake.

• The shell of an egg breaks when it is struck against a hard surface.

Jenny goes to the beach and uses sand to make a sand castle. Which of the following is/are true about the change in the shape of the sand?

I. It is a physical change

II. It makes a new substance

III. It is a chemical change

• II and III only

• I only

• II only

• I and II only

Chemical properties of matter depend mostly on

• the substance's state of matter.

• the shape and size of the substance.

• the types of atoms and bonds that a substance contains.

• the color of the substance.

The chemical reaction shown above takes place in a closed system. What is true about the system while the reaction occurs?

• The total number of particles in the system increases.

• The total number of particles in the system decreases.

• The total mass of the particles in the system stays the same.

• The total mass of the particles in the system increases.