1.A bond in which two atoms share electrons but there is an unequal attraction for the shared electrons is a(n) A. Ionic bond B. Polar covalent bond C. Nonpolar covalent bond D. Hydrogen bond

2. When sodium and chlorine react to produce sodium chloride, an electron is transferred from sodium to chlorine. In this reaction, sodium forms a A.Positive ion B. Negative ion C.Neutral ion D.Radioactive isotope

Before Transfer 11 Protons (+) 11 Electrons (-) After Transfer 11 Protons (+) 10 Electrons (-) Positive Ion Before Transfer 17 Protons (+) 17 Electrons (-) After Transfer 17 Protons (+) 18 Electrons (-) Negative Ion

3. In the chemical equation shown below, the reactants are A. CO 2 (carbon dioxide) and H 2 O (water) B. CO 2 only C. CH 4 (methane) and O 2 D. CH 4 only

4. In the chemical equation shown below, the coefficient (numbers in front of the formula for a molecule) represents Coefficients A.The number of atoms of the first element in the molecule B.The number of valance electrons in the first element C.The number of molecules in the reaction

5. A hydrogen bond is a A. The bond between a hydrogen atom and a oxygen atom in a water molecule B. The bond between a hydrogen atom and a nitrogen atom in an ammonia molecule C. The attraction between opposite poles of polar covalent molecules D. All of the above E. Both A and B

The bond within a water molecule is a polar covalent bond. A hydrogen bond is an attraction between two different water molecules (or other polar molecules). This attraction occurs because the polar covalent bond creates charged poles in each molecule (oxygen end is negatively charged and hydrogen pole is positively charged.) The oxygen end of one molecule is attracted to a hydrogen end of another.

6. Water has a high surface tension due to the force of attraction between the oppositely charged poles of water molecules, forming hydrogen bonds. This exemplifies the fact that water is very A.Adhesive B.Cohesive C.Hydrophobic

Cohesion = the attraction between like molecules Adhesion = the attraction between different molecules Water is both cohesive (between water molecules) and adhesive with many molecules..

7. The term hydrophilic means that a substance A. Is highly reactive B. Is chemically inert (does not react) C. Is attracted to water D. Is repelled by water

8. Which of following types of substances are hydrophilic? I. Nonpolar covalent II. Polar covalent III. Ionic A.I only B.II only C.III only D.I and III E.II and III

Since water is a polar molecule, it attracts both ionic compounds (since charged ions are attracted to the partially charge poles of the water molecule) and other polar compounds (since the oppositely charged poles are attracted to water’s charged poles.)

9.A substance that is able to dissolve another substance is called a A. Solute B. Solvent C. Solution D. Reactant E. Both A and D

10.Water has a _________ specific heat, which means that it changes its temperature _______ than most other substances when the same amount of energy is applied. A.low, more B.low, less C.high, more D.high, less

Specific heat is the amount of energy required to heat 1 gram of a substance by 1°C. Due to the hydrogen bonds between molecules, water has a high specific energy, taking more energy to heat. If the same amount of energy is applied to water another substance, the water will heat up less in most cases.

11.A substance with a low pH is _________ and has a higher concentration of ____ ions. A.Acidic, OH- B.Acidic, H+ C.Basic, OH- D.Basic, H+

12. A substance with a pH of 2 is ____ acidic than a substance with a pH of 6. A.40 x more B.10,000 x more C.40 x less D.10,000 x less

13. Which of the following is the correct shape for a graph comparing the typical effect of temperature on an enzyme catalyzed reaction? A. B. C. D.

14. At very high temperatures, the rate of an enzyme catalyzed reaction decreases because A.The enzyme is moving too quickly to catalyze the reaction B.The enzyme’s active site is saturated C.The enzyme becomes denatured D.The substrate concentration decreases

15. When an enzyme is denatured it has A.Unfolded and lost is shape B.Been chemically broken down

High temperatures can break apart the hydrogen bonds and other interactions that hold a protein in its folded shape. When an enzyme (a protein) loses its shape, it does not have the correct active site for the substrate and is no longer functional.

1. B 2. A 3. C 4. C 5. C 6. B 7. C 8. E 9. B 10. D 11. B 12. B 13.B 14.C 15.A