Grade 8

Category 1 Test

1 Both gypsum and limestone are found in the quarry. Limestone has about the same hardness as calcite. A mineral’s hardness can be determined from how easily it is scratched by another mineral. In a hardness test, what result will show the difference between gypsum and limestone?

F Fluorite scratches limestone and gypsum.G Gypsum scratches talc.H Limestone scratches talc.J Calcite scratches gypsum.

Mohs Scale of Mineral Hardness

Hardness Mineral

1 Talc

2 Gypsum

3 Calcite

4 Fluorite

5 Apatite

6 Orthoclase

7 Quartz

8 Topaz

9 Corundum

10 Diamond

chlorophyll

6CO2 + 6H2O + light energy → C6H12O6 + 6O2

2 Plants use the sun’s energy to make food through photosynthesis. This chemical process is written as the chemical equation shown above. Which of the following lists the three elements that make up the compounds in this equation?

A Chlorophyll, carbon, hydrogenB Carbon, sunlight, oxygenC Carbon, oxygen, hydrogenD Water, oxygen, hydrogen

3 One of the reactions involved in obtaining pure copper (Cu) from copper-containing rock is

Cu2S + O2 → 2Cu + SO2

Which of the following best describes the reaction?

F Copper atoms are used to produce more copper atoms.G Elements are rearranged into new substances.H Atoms of other elements are turned into copper atoms.J Compounds change phase from liquid to gas.

4 How many atoms of oxygen are in one molecule of Mg(ClO)2?

F 1G 2H 3J 4

5 Which of the following best represents the structure of a lithium (Li)

atom?

A C

B D

6 Which letter in this model of a boron atom represents a neutron?

F WG XH YJ Z

7 According to the periodic table, which of the following best represents a carbon atom?

A C

B D

8 How many electrons does gold (Au) have?

F 79G 118H 197J 276

9 Which of the following situations contains an example of a chemical reaction?

A Ice forming after water is placed in a freezerB Watercolor paint drying on paperC A sugar cube dissolving in a glass of waterD A bicycle rusting after it is left in the rain

10 Which of these is an example of a chemical reaction?

F A pot of water boilingG An iron nail rustingH Corn being groundJ Sugar dissolving in tea

Composition of a Few Metal Alloys

11 Which of these metal alloys does NOT contain copper?

A BrassB BronzeC PewterD Steel

Name ofAlloy

Elements in Alloy

Brass Copper and zinc

Bronze Tin and copper

Pewter Lead, antimony, tin, and copper

Steel Iron, chromium, manganese, and carbon

12 Which of the following groups of elements from the periodic table contains only metals?

A Group 12B Group 14C Group 16D Group 18

13 The table above shows the number of protons in an atom of four different elements. According to the periodic table, which of these elements is a metal?

A TB QC XD Z

Element Number of Protons

T 7

Q 15

X 12

Z 17

14 The model shows the structural formula for methane. Which of these is the proper chemical formula for methane?

F 4CHG CH– 4

H 2CH2

J CH4

15 A person was driving across a hot desert in a car without air-conditioning. If all other factors were equal, the temperature inside the car would have been lowest if the car was –

A whiteB redC blueD black

16 Which of the following has the most food energy (calories) per serving?

A PeanutsB Macadamia nutsC CashewsD Pistachios

Peanut Macadamia Nut Cashew Pistachio

Place of Origin Brazil, Peru AustraliaSouth American

Rain ForestMiddle East

Time and Location First Grown in U.S.

Early 1800s Southeastern U.S.

Early 1880s Hawaii

Imported onlyMid-1800s

Southern California

Type of Soil Needed to Grow

Silt, sand, clayOpen sand, lava rock, heavy clay

Sandy Sandy loam

Ideal Soil pH6.0 – 6.5

(slightly acidic)5.5 – 6.5

(slightly acidic)5.5 – 7.0

(acidic to neutral)7.1 – 7.8

(slightly basic)

Ideal Temperature Range (°C)

13 – 30 7 - 26 10 – 40+ 5 – 28

Ideal Amount of Water Needed (cm/yr)

30 – 45 15 – 31 50 – 100 30 – 45

Number of Calories (28g serving)

160 203 160 157

17 A balance and a graduated cylinder are used to determine the density of a mineral sample.

The sample has a mass of 14.7g and a volume of 2.2cm3.

What is the density of the mineral sample?

F 0.15g/cm3

G 32g/cm3

H 13g/cm3

J 6.7g/cm3

18

A researcher wants to experiment with an element that reacts like phosphorus (P) but has a greater atomic mass.

Which element should the researcher select for the experiment?

A Nitrogen(N)B Sulfur(S)C Arsenic (As)D Silicon(Si)

19

A model of an atom is shown below.

An atom of which element is represented by this model?

F Boron(B)G Carbon(C)H Neon (Ne)J Sodium (Na)

20

Which of the following best describes an electron?

A It has no charge and about the same mass as a proton.B It has a negative charge and much less mass than a proton.C It has a positive charge and much more mass than a neutron.D It has a negative charge and about the same mass as a neutron.

21

A scientist spilled a few drops of dilute hydrochloric acid (HCl) on a lab table. For safety purposes, the scientist sprinkled some baking soda (NaHCO3) onto the spill.

Which observation would provide the best evidence that a chemical reaction occurred?

F The baking soda and hydrochloric acid combined, and bubbles formed.G The baking soda absorbed the hydrochloric acid.H Some of the baking soda dissolved in the hydrochloric acid.J The hydrochloric acid evaporated, leaving only the baking soda.

22

Which information could a student determine from only the chemical formula of a protein?

A The color of the proteinB The number of molecules in each sequence that makes up a proteinC The physical arrangement of atoms in the structure of the proteinD The number of atoms of each element in the protein

23

A teacher asks a student to write the chemical equation for photosynthesis. The student’s response is shown below.

The equation is not balanced correctly. Which of these is a balanced equation for photosynthesis?

24

Hay is made up of organic compounds. What are the main elements in many organic compounds?

F Helium, carbon, sodiumG Sodium, hydrogen, nitrogenH Carbon, hydrogen, oxygenJ Radon, oxygen, helium

25

When trying to identify an unknown element, a scientist determines what other elements the unknown element reacts with chemically.

Which property of the unknown element determines the other elements it reacts with?

A The total number of neutrons in the unknown elementB The total number of particles in the nucleus of the unknown elementC The number of protons in the nucleus of the unknown elementD The number of valence electrons in the unknown element

26

The model of the periodic table below shows the locations of four elements.

A student is asked to identify an element that is a pale-yellow brittle solid and does not conduct electricity. At which location in this periodic table would the element most likely be found?

F 1G 2H 3J 4

27

An atom has 25 protons, 30 neutrons, and 25 electrons. What is the charge of the atom’s nucleus?

F +25G +30H −25J −30

28

How many atoms of oxygen are in a molecule of glucose (C6H12O6)?

Record your answer and fill in the bubbles on your answer document.

Be sure to use the correct place value.

29

The chemical equation shown below represents a reaction that produces fuel for certain cars.

Which substance represented in this equation is classified as an element?

A COB H2OC CO2

D H2

30During an investigation, a student combined the two clear, colorless solutions shown below.

The student observed that the temperature changed from 25°C to 23°C when the solutions were combined and that a white substance rapidly formed and settled to the bottom of the container.

What most likely happened to produce these results?

F One of the original compounds came out of solution.G The solutions reacted chemically.H Some of the water froze into ice crystals.J Rapid evaporation of water occurred, leaving a solid.