grade 5 , con 6 , lesson 4

Iron nail will rust when it reacts with...............

• carbon dioxide and water.

• carbon dioxide and vinegar.

• oxygen and vinegar.

• oxygen and water.

Burning of a paper is considered as ...........change of matter.

• only chemical

• only physical

• both physical and chemical

• neither physical nor chemical

Among examples of physical changes is.......

• melting of iron.

• burning of wood.

• making a cake.

• digestion of food

Among chemical unexpected color change is the color that is produced from mixing...........

• baking soda with vinegar.

• iodine with cornstarch.

• food colors with water.

• salt with water.

From the changes that don't form a new substance is..............

• burning of paper.

• cutting of wood.

• baking bread.

• rusting of iron.

All the following examples belong to physical changes, except...........

• cutting a piece of paper.

• melting of ice.

• digestion of food.

• condensation of water vapor.

The change that is produced as a result of iron rusting is the same change produced from............

• melting of ice.

• making bread.

• cutting a piece of cloth.

• breaking of glass.

Exposing an amount of salty water to sunlight for a long time causes.........

• freezing of water.

• formation of a new substance.

• a chemical change to water.

• a physical change to water.

When oxygen combines with carbon and hydrogen,.......... energy is produced

• electrical

• thermal

• kinetic

• solar

Among chemical changes that occurs in cooking is.............

• cutting vegetables.

• boiling of water.

• melting of chocolate.

• baking a bread.