Ingenieria

Chem 170 Exam 1 Review Chapters 1-5

KEY

Instructions: You are allowed to use a scientific calculator to perform mathematical operations. Please silence and put away all cell phones and pagers! Part I. This section is multiple-choice. Fill in the letter corresponding to the best answer on your Scantron form #882.

1. A(n) ______________ is based on a set of well-tested hypotheses and canexplain as well as predict the behavior of a system; whereas a(n) ______________ is based on repeated observations and can predict but cannot explain. A. B. C. D. E. theory, experiment observation, experiment theory, natural law experiment, theory observation, hypothesis

2. A student wrote the following list of observations on his report. One of them is not a true observation, but rather is aninterpretation of an observed result. Which is the interpretation? A. B. C. D. E. “The sodium sulfate and barium nitrate solutions were both clear and colorless.” “Upon mixing the two solutions, a white solid formed.” “The sodium sulfate and barium nitrate reacted with each other.” All of the above are interpretations; none is an observation. All of the above are observations; none is aninterpretation.

3. Silver oxide may be classified as a(n) _____________. A. Element C. Homogeneous mixture B. Compound D. Heterogeneous mixture

4. Hot chocolate with whipped cream may be classified as a(n) _____________. A. Element C. Homogeneous mixture B. Compound D. Heterogeneous mixture

5. The purification of sea water by distillation is a __________ change. A. Chemical B. Physical

6. Sweatcooling your skin by evaporating is a ___________ change. A. Chemical B. Physical

7. Round off 67,175 to 3 significant figures. A. 67,200 B. 671 C. 6.71×10-3 D. 175 E. 6.72

8. Round off 4.9999 to 4 significant figures: A. 4.999 B. 4.000 C. 5 D. 4 E. 5.000

Perform the calculations in problems 9-10. Choose the letter representing the correct answer with the correct number of significantfigures: 9. 20.9 – 1.88 = A. 22.78 B. 22.8 C. 19.0 D. 19.02 E. 19

10.

0.0044 2.633x10-7 A. 16710

= B. 17 C. 1671 D. 1.7×104 E. 1.671×10-10

11. Convert 62,300 to scientific notation. A. 62.3×103 B. 6.2300×104 C. 6.23×104 D. 6.23×10-4 E. 6.23×10-3

12. Convert 0.0091 to scientific notation. A. 9.1×10-3 B. 9.1×103 C. 91×10-4 D. 0.91×10-2 E. 9.100×10-3

13. Convert 4.3×10-2 to standardnotation. A. 0.0043 B. 4.3 C. 430 D. 43 E. 0.043

14. Convert 47.0ºC to ºF. A. 116.6ºF B. 8.33ºF C. 320.ºF D. 29.2ºF E. 116ºF

15. The __________ and __________ contribute most to the mass of an atom, while the _____________ determines the atom’s chemical behavior. A. B. C. D. E. proton, neutron, electron proton, electron, neutron neutron, electron, proton proton, photon, neutron none of theabove

16. The symbol 63 Cu represents an isotope of the element copper. Give the following values: 29 atomic number, mass number, number of neutrons, number of electrons, and number of protons.
A. B. C. D. E. atomic # 63 63 29 29 29 mass number 29 29 63 63 92 # of neutrons 34 63 29 34 63 # of electrons 63 63 63 29 29 # of protons 63 29 63 29 29

17. Which of the following statements aboutisotopes is/are correct?

i. ii. iii. iv. v.

They have different masses. They have different numbers of neutrons. They have different electrical charges. They have different numbers of protons. They have different mass numbers.
B. i, ii, and iv E. All are correct C. i, ii, and v

A. i and ii D. i, ii, iv, and v

18. There exist two stable isotopes of boron, and the average mass of a boronatom is 10.81 amu. Assuming you were able to isolate only a single boron atom, the chance that you would randomly get one with a mass of 10.81 amu is A. 0% B. 0.81% C. about 50% D. 10.81% E. 100%

19. Match the fundamental charge and mass with the appropriate subatomic particle: Charge = –1 Mass ≈ 0 amu proton proton electron electron neutron Charge = +1 Mass ≈ 1 amu neutron electron proton...