click below
click below
Normal Size Small Size show me how
Grade 8 Chemistry
Released Test Items
Question | Answer |
---|---|
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... | Elements cannot be changed to other elements by physical or chemical means. |
Which of the following molecules does not contain three atoms? | N2 |
A substance made up of two or more elements that have been chemically combined is called... | A compound |
A solution may be prepared by dissolving crystals of a salt in water. Which of the following would probably not affect the rate of solubility? | Reducing the air pressure on the solution. |
A compound is a molecule made up of atoms from at least two elements. Which of the following gases is a compound? | Methane (CH4) |
A proton has which of the following charges? | Positive |
Which of the following materials is composed of only one kind of atom? | Helium |
Which picture illustrates the structure of a molecule of water? | H \ O / H |
Mercury is a liquid metal that is used in many thermometers. The mercury in the thermometer rises because it... | Expands when heated. |
Which of these best shows that calcium is different from all other elements? | Its number of protons. |
In a experiment combining vinegar and baking soda, gas is given off. In this chemical reaction, the vinegar and baking soda are... | Reactants. |
Which of these cannot be separated into its parts by an ordinary chemical or physical process? | An atom of carbon (C) |
The atom is composed of electrons, protons, and neutrons. What is the electric charge on the neutron? | 0 |
Compounds are made up of more than one element. Which of the following represents a compound? | NH3 |
Calcium metal (Ca) can be produced by passing an electric current through molten calcium chloride (Ca12). Chlorine gas (C12) is also formed. What is the balanced equation for this reaction? | CaCl2->__Ca+Cl2 |
Which of these belongs in the outermost shell (energy level) of an atom? | Electrons. |
When plants perform photosynthesis, they use sunlight to produce food. This is an example of light energy being converted to... | Chemical Energy. |