Answers AZ-Physical Science A-CRUnit Test

Unit Test — Unit test Answers

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An atom of the element zinc has an atomic number of 30 and a mass number of 65. How many protons does an uncharged zinc atom have?

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Which is most likely a physical change?

cutting a substance into four pieces

burning a substance into ash and smoke

reacting a substance chemically to form a new substance

combining a substance with water to make rust

Which procedure would best allow a scientist to observe a chemical property of hydrochloric acid (HCl) solution?

cooling the HCl solution until it becomes solid, and measuring this temperature

adding zinc to the HCl solution and observing whether or not bubbles are produced

placing a conductivity probe into a beaker of HCl solution to determine if it conducts electricity

measuring the mass of and volume of a sample of HCl solution to find its density

Which describes a feature of the physical changes of all substances?

can dissolve in water

can conduct heat and electricity

rearranges atoms to form new substances

does not change the identity of a substance

Suppose that a substance in a beaker is heated over a burner in a science lab. Which observation would most likely indicate that a chemical change has occurred in the substance?

If the substance is a liquid or solid, an increase in temperature would indicate a chemical change.

If the substance is a liquid, a change of some of the liquid to gaseous form would indicate a chemical change.

If the substance is a solid, a change of some of the solid to liquid form would indicate a chemical change.

If the substance is a liquid or solid, production of an odor would indicate a chemical change.

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