Chemical Reactions
  • 1. A chemical change is different than a physical change because in a chemical change
A) Molecules do not physically touch
B) A new substance is formed and in a physical change no new substance is formed
C) The change can be seen but in a physical change it cannot
D) Chemicals are used
  • 2. In a chemical reaction
A) Some atoms disappear while others multiply to form the products
B) The atoms of the reactants unbond, rearrange, and then rebond to form the products
C) The atoms of the reactants always stay together to form the products
D) New atoms are formed which combine to make the products
  • 3. In the chemical reaction CH4 + 2O2 → CO2 + 2H2O, there are reactants on the left of the equation and products on the right. If you count the atoms in the reactants, there are
A) 4 carbon atoms, 4 hydrogen atoms, and 4 oxygen atoms
B) 4 carbon atoms, 4 hydrogen atoms, and 2 oxygen atoms
C) 1 carbon atom, 4 hydrogen atoms, and 2 oxygen atoms
D) 1 carbon atom, 4 hydrogen atoms, and 4 oxygen atoms
  • 4. In a chemical reaction, mass is conserved. This means that
A) The type and number of atoms in the reactants equals the type and number of atoms in the products
B) The mass of the products stays the same during a chemical reaction
C) The mass of the reactants stays the same during a chemical reaction
D) The mass of the products is always twice the mass of the reactants.
  • 5. If more reactants are used in a chemical reaction, then more products will be produced. This means
A) Too many products can slow down the reaction
B) More reactants have more atoms to react to form more products
C) More reactants take up the same volume
D) More reactants cause the reaction to heat up
  • 6. If two substances react and the temperature of the mixture increases, the reaction is
A) Endothermic
B) Exothermic
C) One that needs a catalyst
D) Not one that produces anything new
  • 7. If a reaction is exothermic,
A) The temperature goes down
B) It takes more energy to break the bonds of the reactants than is released when the bonds in the products are formed
C) More energy is released when the bonds in the products are formed than is used to break the bonds in the reactants
D) The same amount of energy is used to break the bonds of the reactants as is released when the bonds in the products are formed
  • 8. Redox reactions involves exchange of
A) Electrons between atoms
B) Neutrons between atoms
C) Neutrons between atoms
D) Neurons between molecules
  • 9. NADH is the ______ form of NAD+.
A) neutral
B) charged
C) reduced
D) oxidized
  • 10. Oxidation is the _____ of electrons while reduction is the _______ of electrons.
A) loss; gain
B) gain; loss
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