Unit 1: Review (Test Wizard)

A sample of a substance is heated strongly in a

crucible and the sample increases in mass. This is

evidence that the substance has

• melted

• sublimed

• evolved a gas

• expanded

• undergone a chemical change

Carbon is classed as an element rather than as a

compound because it

• has been known for many centuries

• combines with oxygen to form a gas

• cannot be chemically decomposed into two or

  more substances

• is formed when wood is heated without the

  presence of air

• can be found in many pure forms

An element is identified most accurately by its

• mass and color

• volume and odor

• color and conductivity

• density and color

• density and conductivity

Which is a gas at room temperature?

• O2 (oxygen)

• NaCl (sodium chloride)

• C12H22O11 (sucrose)

• H2O (water)

• Br2 (bromine)

Which substance contains only one kind of atom?

• water

• graphite

• ammonia

• sulfuric acid

• salt

Molecules of the inert gases are

• amorphous

• diatomic

• ionic

• monatomic

• reactive

An example of a decomposition reaction is

• Zn(s) + CuSO4(aq) -> ZnSO4(aq) + Cu(s)

• (NH4)2CO3(s) -> 2 NH3(g) + H2O(g) + CO2

  (g)

• Ca(s) + 2 H2O(l) -> Ca(OH)2(aq) + H2(g)

• NaCl(aq) + AgNO3(aq) -> NaNO3(aq) +

  AgCl(s)

• (NH4)2CO3(s) -> (NH4)2CO3(l)

The reaction in which mercury is formed by heating

its oxide is known as a

• synthesis

• decomposition

• reverse reaction

• double decomposition

• single replacement

A chemical change involves

• a change in color

• a change of state

• a change in density

• a change in the number of atoms

• the formation of a new pure substance

Pure substances

• are heterogeneous

• have three visible phases

• have variable composition

• have constant physical properties

• have variable chemical properties