Science as Inquiry and Physical/Chemical Changes

One type of cold remedy is an effervescent tablet that breaks down in water.  When the tablet is placed in water, it forms gas bubbles.  In this example, the formation of gas

• is a physical property
• occurs when adding water to acid
• is a sign of a chemical change
• occurs wwhen the water boils

A type of cold pack has two seperate sections inside. One section contains a liquid and the other section contains a powder.  When the cold pack is squeezed, the liquid and powder mix, making the pack become cold.  Which is the best explanation of why the pack gets cold?

• a mixture forms
• a solution forms
• a chemical change occurs
• thermal energy is used

Campers burn logs in a campfire.  How will the campers know that a chemical change has taken place?

• The logs changed shape
• The rocks glowed when heated
• The wood became a different substance
• The ground absorbed heat from the coals

Over time iron becomes rust when combines with water and oxygen.  Which type of change must occur for rust to form?

• chemical
• mechanical
• nuclear
• physical

Which property of sugar remains after sugar is dissolved in water?

• color
• taste
• shape
• texture

Sam lost his hammer outside and when he found it , parts of it were covered in brown, flaky crust.  Which type of change occurred when rust formed on the hammer?

• chemical
• electrical
• thermal
• physical

Which example BEST describes a physical change?

• baking a pie
• burning a candle
• making a paper airplane

Glenn accidentally left his crayon box in the car on a hot day.  Which BEST explains what happened to his crayons? 

• crayons melted; changed from solid to liquid
• crayons melted; changed from liquid to solid
• crayons evaporated; changed from liquid to solid

 A glass of salt water is put on a windowsill.  After a week the water is gone and there is a film of white crystals left on the bottom of the glass.  Which BEST explains what happened?

• The salt caused the water to dry up
• The water evaporated and left the salt behind
• The water and the salt evaporated and left a film behind. 

Which example BEST describes a physical change?

• iron rusting
• charcoal burning
• an ice cube melting
• a marshmallow burning