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Water changing to ice is considered a [ Select ] ["physical", "chemical"] change whereas iron changing to rust is considered a

Water changing to ice is considered a                              [ Select ]                          ["physical", "chemical"]            change whereas iron changing to rust is considered a                              [ Select ]                          ["chemical", "physical"]           change.

 

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Question 2

5 pts

How can you show that water is a compound rather than a homogeneous mixture of hydrogen and oxygen? Select all that apply!

show that the freezing and boiling points of water are fixed temperatures

decompose water into two parts hydrogen gas for each part oxygen gas

demonstrate that water cannot be separated into its components by physical changes like freezing and boiling

 

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Question 3

5 pts

The most abundant element in the universe is   and the most abundant element in the human body is   .

 

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Question 4

5 pts

Classify the following elements as metalnonmetal, or metalloid.

a. Lithium:                              [ Select ]                          ["metal", "metalloid", "nonmetal"]           

b. Titanium:                              [ Select ]                          ["metal", "nonmetal", "metalloid"]           

c. Bromine:                              [ Select ]                          ["nonmetal", "metal", "metalloid"]           

d. Cadmium:                              [ Select ]                          ["metal", "nonmetal", "metalloid"]           

e. Silicon:                              [ Select ]                          ["nonmetal", "metal", "metalloid"]           

f. Mercury:                              [ Select ]                          ["metal", "nonmetal", "metalloid"]           

g. Nitrogen:                              [ Select ]                          ["metalloid", "nonmetal", "metal"]           

h. Iodine:                              [ Select ]                          ["metal", "metalloid", "nonmetal"]           

i. Strontium:                              [ Select ]                          ["metalloid", "metal", "nonmetal"]           

j. Sodium:                              [ Select ]                          ["metalloid", "metal", "nonmetal"]           

 

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Question 5

5 pts

The element astatine (At), which appears at the bottom of the halogen column in the periodic table, has been prepared artificially in minute amounts but has not been found in nature. Using the periodic law and your knowledge of the halogens, predict the properties of this element, as follows:

I. What is the formula for its compounds with hydrogen?

a.HAtb.AtHc.H2At

Answer:                              [ Select ]                          ["a.", "c.", "b."]           

II. What is the formula for its compounds with potassium?

a.KAtb.AtKc.K2At

Answer:                              [ Select ]                          ["c.", "b.", "a."]           

III. What is the formula for its compounds with calcium?

a.CaAtb.AtCac.CaAt2

Answer:                              [ Select ]                          ["b.", "c.", "a."]           

IV. Is its compound with potassium more or less stable than potassium iodide?

Answer:                              [ Select ]                          ["more stable", "less stable"]           

 

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Question 6

5 pts

Order the following metals according to increasing chemical activity: cesiumpotassiumsodiumcalciummagnesium.

least active                            [ Select ]                          ["potassium", "magnesium", "cesium", "calcium", "sodium"]                                       [ Select ]                          ["calcium", "magnesium", "cesium", "potassium", "sodium"]                                       [ Select ]                          ["calcium", "potassium", "cesium", "magnesium", "sodium"]                                       [ Select ]                          ["sodium", "calcium", "cesium", "potassium", "magnesium"]           most active                            [ Select ]                          ["potassium", "sodium", "magnesium", "cesium", "calcium"]           

 

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Question 7

10 pts

Label the following compounds as either ionic or covalent:

LiF                            [ Select ]                          ["covalent", "ionic"]           MgS                            [ Select ]                          ["ionic", "covalent"]           NO2                            [ Select ]                          ["covalent", "ionic"]           SiF4                            [ Select ]                          ["covalent", "ionic"]           Na2S                            [ Select ]                          ["covalent", "ionic"]           CCl4                            [ Select ]                          ["ionic", "covalent"]           RbCl                            [ Select ]                          ["ionic", "covalent"]           Ca3N2                            [ Select ]                          ["ionic", "covalent"]           H2O                            [ Select ]                          ["covalent", "ionic"]           XeF6                            [ Select ]                          ["covalent", "ionic"]           

 

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Question 8

5 pts

Why do inert gas atoms almost never participate in covalent bonds?

The inert gas molecules are too far apart to share electrons with other elements.

The inert gases contain closed outer shells and filled inner shells, leaving no shell to accommodate a donated electron.

The inert gases contain closed outer shells and filled inner shells, leaving no shell to accommodate a shared electron.

The inert gas molecules have no outer shells to accommodate donated electrons.

 

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Question 9

10 pts

Name the following compounds.

a. KClb. Ca(OH)2c. N2O5d. XeF6e. CO

 

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Question 10

10 pts

Insert the missing numbers in the following equations:

a. Ca +   H2O → Ca(OH)2 + H2

b. 2Al +   H2SO4 → Al2(SO4)3 + 3H2

c. C7H16 + 11O2 → 7CO2 +   H2O

d. 6H3BO3 → H4B6O11 +   H2O

 

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Question 11

10 pts

Insert the missing numbers in the following equations:

a. 4NH3 + 3O2 → 2N2 +    H2O

b. 4NH3 + 5O2 → 4NO +   H2O

c. 4FeS2 + 11O2 → 2Fe2O3 +   SO2

d. 2HNO3 + 3H2S → 2NO3 +   H2 + 3S

 

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Question 12

5 pts

Find the balanced equation when calcium hydride reacts with water to give gaseous hydrogen and calcium hydroxide.

a.CaH2 + 2H2O → Ca(OH)2 + 2H2b.4CaH2 + 2H2O → 2Ca2(OH)2 + 4H2c.2CaH2 + 2H2O → Ca2(OH)2 + 3H2d.2CaH2 + 8H2O → 4Ca(OH)2 + 8H2

Answer:                              [ Select ]                          ["a.", "b.", "c.", "d."]           

 

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Question 13

5 pts

Which of the following equations is balanced when aluminum reacts with gaseous chlorine to give aluminum chloride?

1.2Al + 3Cl2 → Al2Cl62.2Al + 3Cl2 → Al4Cl63.5Al + 4Cl2 → 4AlCl24.2Al + 3Cl2 → 2AlCl3

1

2

3

4

 

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Question 14

5 pts

Properly balance the chemical equation describing the break down of potassium chlorate into potassium chloride and oxygen gas by adding the appropriate chemical formulas and/or coefficients. Since you can't easily do subscripts, just worry about putting the appropriate number after the chemical symbol (for example, type O2 to represent O2). If you are given two boxes side-by-side, use the first for the coefficient and the second for the chemical formula.

  →   +   O2




please show work


thanks!

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