8th Grade Science Released Tests

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
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.
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.
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
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
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.
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
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
A proton has which of the following charges?
1. Negative
2. Neutral
3. Positive
4. Magnetic
Which of these is best classified as a mixture?
1. Carbon dioxide
2. Water
3. Soil
4. Iron
Which of these belongs in the outermost shell (energy level) of an atom?
1. Electrons
2. Protons
3. Neutrons
4. Photons
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
Which of these minerals is a carbonate?
1. Calcite (CaCO₃)
2. Galena (PbS)
3. Gypsum (CaSO₄)
4. Magnetite (Fe₃O₄)
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
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.
Which of the following are products of combustion?
1. Heat and light
2. Newly discovered elements
3. Liquid and solid water
4. Additional atoms

8th Grade Science Released Tests - Matter Review 2