PHY-102-Chemistry Exercises Assignment PDF

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multiple choice answers and descriptive answers...

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PHY-102: Chemistry Exercises Complete the following exercises. 1. Which of the following are physical properties? (Select all that apply) A. Color B. Hardness C. Density D. Flammability E. Conductivity F. Reactivity with other materials 2. Which of the following describe a physical change? (Select all that apply) A. Photosynthesis B. Evaporation of alcohol when a table is wiped with an alcohol swab C. Burning of firewood D. Rusting of iron E. Breaking a glass F. Melting ice 3. Which of the following are chemical properties? (Select all that apply) A. Texture B. Toxicity C. Conductivity D. Density E. Flammability F. Reactivity with other materials 4. Which of the following describe a chemical change? (Select all that apply) A. Melting of ice B. Evaporation of alcohol when a table is wiped with an alcohol swab C. Burning of firewood D. Rusting of iron E. Breaking a glass F. Cooking an egg 5. Match the following substances with the best classification: © 2014. Grand Canyon University. All Rights Reserved.

1. 2. 3. 4. 5.

Magnesium (B.) Salt water (C.) Blood (E.) Carbon dioxide (A.) Soil sample (D.)

A. B. C. D. E.

Compound Element Solution Heterogeneous mixture Suspension

6. Which of the following illustrations best illustrate an element, a compound, and a mixture. Provide an explanation for your choices.

(6.) C - element, it is made up of the same type of particles. A - compound, all the particles have same configuration, and the ratio is fixed. B - mixture, as the configuration is non uniform also the ratio is not fixed. 7. Describe a method to separate the substances in a solution. (7.) There are several ways to separate substance from solutions and sometimes we use them on a daily basis. When each substance hits its boiling point, it causes it to separate the substance from the mixture solution. This process is called distillation, every substance has a different boiling point. 8. Distinguish between a saturated and an unsaturated solution. (8.) Solutions with maximum solute concentration is known as saturated and all other solutions which have lower concentration than saturated solutions are said to be unsaturated solutions. \ © 2014. Grand Canyon University. All Rights Reserved.

9. Match the following: 1. Sodium chloride, NaCl (D.) 2. Oxygen, O2 (C.) 3. Methane, CH4 (E.) 4. Lithium (A.) 5. Air (B.) A. B. C. D. E.

Element Solution Diatomic gas Ionic compound Covalent compound

10. Electron dot diagrams are a way to illustrate the number of valence electrons for an element. The symbol for the element is surrounded by a dot for each valence electron. Match the following electron dot diagrams with an element:

1. 2. 3. 4.

Electron dot diagram #1 (C.) Electron dot diagram #2 (D.) Electron dot diagram #3 (B.) Electron dot diagram #4 (A.)

A. B. C. D.

Sodium, Na Aluminum, Al Fluorine, F Nitrogen, N

11. For the following questions consider a compound of calcium and chlorine. a. What type of bond do calcium and chlorine form? (a.) Calcium is a metal and chlorine is a non-metal therefore ionic bond exists. b. Describe how this bond forms. (b.) Calcium = 20 = 1s22s22p63s23p64s2 Chlorine = 17 = 1s22s22p63s23p5 Calcium 4s electrons excites then the compound will form. c. What is the chemical formula for the compound? Explain. © 2014. Grand Canyon University. All Rights Reserved.

(c.) CaCl2 12. For the following questions consider a water molecule, H2O. a. What type of bond is formed between the oxygen and the hydrogen atoms? (a.) Covalent bond exists between hydrogen and oxygen. b. Describe how these bonds form. (b.) Oxygen atomic no = 8, Hydrogen atomic no is = 1, Electronic configuration is = 1s1. Electronic configuration is = 1s22s22p4. Two hydrogen and one oxygen will participate in the bond and as whole as a product water molecule will form. c. Explain why there are two hydrogen atoms for each oxygen atom. (c.) Two hydrogens have only one electron but to form a bond with oxygen two electrons required. That is why two hydrogens are need for one oxygen. 13. For the following questions consider a piece of copper wire. a. What type of bond is formed between the copper atoms? (a.) A metallic bond is formed in copper wire and it is also called as semi covalent bond. b. Describe how these bonds form. (b.) c. Explain why copper is a good electrical conductor. (c.) Copper is a good electrical conductor due to the free electrons moving in them these electrons are also called conduction electrons. 14. Explain why food stays fresh longer when kept in the refrigerator. (14.) Cold temperatures help food stay fresh for longer periods of time. Refrigeration is used to slow down the activity of bacteria so that it takes longer for the bacteria to spoil the food. 15. In the stratospheric level of the atmosphere there is a high level of ozone, O3. This ozone absorbs much of the ultraviolet light from the sun and thus protects life in the surface of the Earth from harmful high level of ultraviolet radiation. Explain why one chlorofluorocarbon (CFC) molecule in the ozone layer is capable of breaking down hundreds and even thousands of ozone molecules? (15.) Chlorofluorocarbons are very stable atoms. They cannot be removed from lower atmosphere or they will not dissolve in water. Wind moved them into stratosphere over long time. They can be broken down only when they are exposed to ultraviolet radiation. Then they release atomic chlorine which can destroy thousands of ozone atoms.

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16. Balance the following chemical reaction by placing the proper coefficients in front of each reactant and in front of the product.

a. What is the coefficient on line (a)? (a.) 4 b. What is the coefficient on line (b)? (b.) 2 c. What is the coefficient on line (c)? (c.) 2 17. Acetylene gas (C2H2) burns in the oxyacetylene torch for welding. Balance the chemical reaction by placing the proper coefficients in front of each reactant and each product.

a. What is the coefficient on line (a)? (a.) 2 b. What is the coefficient on line (b)? (b.) 5 c. What is the coefficient on line (c)? (c.) 4 d. What is the coefficient on line (c)? (d.) 2

The remaining questions are multiple-choice questions:

18. What is a substance made up of only one type of atom called? A. An element B. A mixture C. A solution D. A compound E. A nucleus 19. Which of the following is a solution? A. Table salt © 2014. Grand Canyon University. All Rights Reserved.

B. C. D. E.

Nitrogen A vinegar and oil salad dressing Copper wire A 14 karat gold ring

20. Which of the following is a heterogeneous mixture? A. Table salt B. Air C. A vinegar and oil salad dressing D. Steel E. A 14 karat gold ring 21. On a container of chicken broth you notice the instructions to “shake well before serving.” Which of the following best describes the chicken broth? A. A solution B. An element C. A compound D. A suspension E. A pure substance 22. The formation of an ionic bond involves: A. A transfer of electrons B. A transfer of protons C. A transfer of neutrons D. A sharing of electrons E. A sharing of protons 23. Which of the following is the chemical formula for the ionic compound magnesium nitride? A. MgN B. Mg2N C. Mg2N3 D. Mg3N2 E. MgN2 24. Which of the following is correct about a molecule of carbon trichloride? A. It has one carbon atom for each chloride atom. B. It has three chloride atoms for each carbon atom. C. It has three carbon atoms for each chloride atom. © 2014. Grand Canyon University. All Rights Reserved.

D. It is a mixture of equal parts carbon and trichloride. E. It is a solution of carbon in chlorine. 25. What is the term for the substances that undergo a change in a chemical reaction? A. Solutions B. Products C. Solvents D. Catalysts E. Reactants

26. When methane (CH4) burns it combines with oxygen and forms carbon dioxide and water. Which of the following is the balanced chemical reaction for the burning of methane? A. B. C. D.

CH4 + O2 → CO2 + H2O 3 CH4 + 6 O2 → 3 CO2 + 6 H2O 2 CH4 + 3 O2 → CO2 + 4 H2O CH4 + 3 O2 → 2 CO2 + 2 H2O E. CH4 + 2 O2 → CO2 + 2 H2O

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