8th Grade Science Released Tests

ATOMS, ELEMENTS, COMPOUNDS
1. B
2. V
3. C
4. X
How is the modern model of an atom different from the Bohr atomic model?
1. The masses of the atomic particles are different.
2. The numbers of electrons are different.
3. The shapes of the nuclei are different.
4. The arrangements of the electrons are different.
The diagram above shows a block from the periodic table. The number six represents the —
1. atomic mass of the element carbon
2. atomic number of the element carbon
3. number of neutrons in the element carbon
4. number of valence electrons in the element carbon
(2004) Which of these belongs in the outermost shell (energy level) of an atom?
1. Electrons
2. Protons
3. Neutrons
4. Photons
(2003) Several centuries ago, men called alchemists tried to transform common metals into gold. Even though they tried many different chemical and physical methods, they never succeeded because —
1. they could not heat common metals to extremely high temperatures
2. the common metals they worked with were not pure
3. they did not add the correct material to the common metal
4. elements cannot be changed to other elements by physical or chemical means
(2004) Which of the following lists the elements in order, from those having the least protons to those having the most protons in the atoms?
1. O, N, B, Li
2. Na, S, Al, Cl
3. O, S, Se, Te
4. Rb, K, Na, Li
(2003) Which picture illustrates the structure of a molecule of water?
(2004) A substance made up of two or more elements that have been chemically combined is called —
1. an atom
2. a compound
3. an element
4. a mixture
(2003) The atom is composed of electrons, protons, and neutrons. What is the electric charge on the neutron?
1. -1
2. +1
3. 0
4. +2
(2004) Which of these minerals is a carbonate?
1. Calcite (CaCO₃)
2. Galena (PbS)
3. Gypsum (CaSO₄)
4. Magnetite (Fe₃O₄)
(2003) Which of the following elements belongs to the family indicated?
1. Nitrogen belongs to the halogen family.
2. Helium belongs to the noble gas family.
3. Calcium belongs to the alkali family.
4. Sodium belongs to the alkaline earth family
(2004) Which of these is best classified as a mixture?
1. Carbon dioxide
2. Water
3. Soil
4. Iron
(2003) Which of these elements has an atomic number of 14?
1. N
2. Al
3. Si
4. P
(2004) A proton has which of the following charges?
1. Negative
2. Neutral
3. Positive
4. Magnetic
Because zinc can combine with other substances but cannot be changed into a simpler substance by an ordinary chemical process, zinc is classified as —
1. a compound
2. a mixture
3. an element
4. an acid
A student makes a drawing of a carbon atom. Which of these should the student show in the nucleus of the atom?
1. Ions
2. Protons
3. Electrons
4. Molecules
Which of these substances is an element?
1. Steel
2. Chlorine
3. Plastic
4. Sugar
In the chemical formula for ammonia, , what does the subscript 3 represent?
1. The number of nitrogen and hydrogen atoms in each molecule of ammonia
2. The number of hydrogen atoms in each molecule of ammonia
3. The number of ammonia molecules that will bond together
4. The number of nitrogen atoms in each molecule of ammonia
PHYSICAL CHANGES - PHASE CHANGES
1. HH
2. H
3. H
4. H
After fishing in the ocean, a student left his fishing gear in the sun to dry. Later, he noticed that small white crystals had formed on the rod, reel, and fishing line. Which of these is the best explanation of what occurred?
1. The water evaporated from the fishing gear, and sand was attracted to it.
2. The fish that were caught left scales on the fishing gear.
3. The salt in the ocean water reacted with the fishing gear and caused it to rust.
4. The water evaporated from the fishing gear, and salt from the ocean was left behind.
(2003) Mercury is a liquid metal that is used in many thermometers. The mercury in the thermometer rises because it —
1. is sucked upward by vacuum
2. expands when heated
3. is compressed by air pressure
4. increases in density when heated
(2003) Which of these will cause water to change to ice?
1. Removing heat from the water
2. Stirring the water
3. Adding salt to the water
4. Putting the water in the sunlight
Which process is a physical change?
1. Rusting iron
2. Burning coal
3. Tarnishing silver
4. Melting ice
Expansion joints such as these are put on bridges because the concrete expands and contracts. This happens when —
1. chemicals get on the concrete
2. the temperature changes
3. the amount of light changes
4. the concrete gets wet
(2003) Which of the following is a physical property of copper?
1. Ductile, can be drawn into a wire
2. Liquid at room temperature
3. Readily reacts with water to form an acid
4. Readily reacts with oxygen
Which of these best describes the particle motion taking place as gas is exposed to freezing temperatures?
1. The particles decrease in speed.
2. The particles move with more force.
3. The motion of the particles becomes random.
4. The motion of the particles is unchanged.
(2003) Tearing paper is an example of a —
1. physical change
2. chemical change
3. chemical reaction
4. solution
Of the states of matter, gas is the only state that —
1. is fluid
2. has mass
3. is highly compressible
4. has a definite shape
(2004) If you break a piece of glass, the shape of the glass changes, but the properties in the fragments remain the same. Which of the following has occurred?
1. A chemical change
2. A temperature change
3. A phase change
4. A physical change
CHEMICAL CHANGES
1. B
2. B
3. B
4. B
According to this equation, what happened to the carbon and oxygen?
1. They combined chemically to form a new compound.
2. They combined chemically to form carbon and oxygen.
3. They combined physically to form a new mixture.
4. They combined physically to form a new element.
(2004) Calcium metal (Ca) can be produced by passing an electric current through molten calcium chloride (CaCl₂). Chlorine gas (Cl₂) is also formed. What is the balanced equation for this reaction?
1. 2CaCl → Ca + 2Cl
2. CaCl₂ + H₂O → Ca + ClH + O₂
3. CaCl₂ + Cl → Ca + Cl₃
4. CaCl₂ → Ca + Cl₂
Which of the following are products of combustion?
1. Heat and light
2. Newly discovered elements
3. Liquid and solid water
4. Additional atoms
(2003) Which of these is a change in chemical composition?
1. A lake freezes solid.
2. Gravel, sand, and water are mixed.
3. A copper bar is rolled into a flat sheet.
4. Vinegar bubbles when baking soda is added.
OTHER MATTER
1. M
2. M
3. M
4. M
When a base is mixed with an acidic solution, neutralization occurs because the —
1. base reaches absolute zero
2. acid evaporates
3. base chemically reacts with the acid
4. mass of the solution increases

8th Grade Science Released Tests - Matter