Exam # 1 Chem 121.09 Spring 2012
Name ________________________________________________
Mark the following multiple choice questions with the one best answer from the given choices.
_D__1. Which of the following is NOT the same as 15 µL?
A) 1.5 X 10-8 KL B) 0.015 mL C) 1.5 X 10-5 L D) 1,500 nL E) none of these
_A__2. Which of the following would NOT be a physical property
A) Combines with oxygen
B) Viscosity (COUNTED THIS AS HALF POINT BECAUSE OF CONFUSION)
C) A blue liquid
D) Has a mass of 25 grams
E) None of the above are correct answers
_D__3. In order, what is the freezing point, approximate room temperature and boiling point of water in the Kelvin
scale?
A) 32-75-212 B) 0-75-100 C) 0-25-100 D) 273-298-373 E) none of these
__B__4. If you hold a solid piece of pure gallium metal in your hand, your body heat will melt the
gallium into its liquid form. This illustrates which of the following?
A) distillation B) physical change C) chemical change
D) chemical property E) none of the above
__C__5. Which of the following terms correctly applies to a molecule of O3?
A. triatomic, heteroatomic
B. polyatomic, diatomic
C. triatomic, homoatomic
D. diatomic, heteroatomic
__E__6. The distance between the two hydrogen atoms in a molecule of water is 0.000000172 m.
Which of the following correctly expresses this distance in scientific notation?
A) 1.72 µm B) 1.72 × 10-10 m C) 1.72 × 10-4 mm
D) 172 nm E) more than one answer is correct (COUNTED C & D AS 0.8 PTS SINCE THEY WERE
THE CORRECT ANSWERS)
_D__7. Which of the following sets of units is NOT in the order of increasing size?
A) μg < g < kg
B) mL < dL < L
C) ns < ms < s
D) cm < μm < km
E) μmol < mmol < mol
__C__8. Which value below has the fewest number of significant digits?
A) 1.0035 B) 17.000 C) 0.0000625 D) 6.022 X 1023
__A__9. Knowing that 2.54 cm = 1 inch, 1 m = 100 cm and 36 in = 1 yard, calculate the number of m in 2.5 yards.
A) 2.3 B) 35 C) 0.98 D) 2.3 X 102 E) 2.7 X 10-2
__B___10. A sample of orange juice has a mass of 298 g and a density of 1.12 g/cm3. What is the sample volume?
A) 3.76 X 10-3 cm3 B) 266 mL (OK SINCE mL and cm3 ARE THE SAME) C) 334 mL D) 334 cm3
__C___11. Do the following calculation and express the answer using the correct number of significant figures.
(9.21 X 10-3 + 1.3 X 10-3) X 6.453 =
A) 0.07 B) 0.068 C) 0.0678 D) 0.06782 (ADD NUMBERS FIRST – ANSWER = 10.5 X 10-3) SINCE THIS
HAS 3 SIG FIGS, FINAL ANSWER HAS 3 SIG FIGS
__B___12. Which of the following is NOT a correct representation of a proton?
A) p B) po C) p+ D) H+ E) all of these are correct
_D____13. Which of the following does NOT correctly describe atoms and subatomic particles?
A) Electron orbitals take up most of the space in an atom
B) almost all the mass of an atom is in the nucleus
C) atoms are mostly empty space
D) normal, neutral atoms always contains the same number of protons and neutrons
E) all of these are correct
___B__14. The formula CH4 would be classified as:
A) an element containing 5 atoms.
B) a compound containing atoms of two elements.
C) a homogenous mixture of two elements.
D) a homogenous mixture of two compounds.
__B___15. A specific isotope of an element is known to have 15 protons and 16 neutrons. Which symbol
would properly represent this isotope?
31
31
S E) none of these are correct
A) 15
B) 15
D) 16
P C) 16
15 X
31 Ga
_C____ 16. IF the atomic weight of Cl was reported as 36.89 grams, which of the following possible isotopes
would you expect to have the greatest natural abundance?
A) Cl-35 B) Cl-36 C) Cl-37 D) all are about equal in abundance E) none of these are correct
__C___ 17. The atomic mass unit is defined as:
A) the mass of the hydrogen atom containing only one proton.
B) the mass of electrons found in a carbon atom containing six protons and neutrons.
C) 1/12 the mass of a carbon atom containing six protons and six neutrons.
D) the mass of a neutron
E) none of the above
__C___18. How many total atoms are in the formula NH4NO3?
A) 4 B) 7 C) 9 D) 12 E) 14
__A_19. A metallic cylinder has the following characteristics when determined in our chemistry laboratory:
Weight = 1.2 lb, mass = 0.55 kg, volume = 15. 4 mL. Which characteristic would be different
(if any) when determined on the moon.
A) weight B) mass C) volume D) density E) none of these would be different
20. Give an example of each of the following. If your answer might be considered differently by different people,
give an explanation.
A) a diatomic compound – ANY 2-ATOM FORMULA WITH DIFFERENT ELEMENTS
EXAMPLE CO
B) an element ANY ELEMENT SYMBOL OR FORMULA
EXAMPLES Fe, O, O2
C) a homogeneous mixture - ONE EXAMPLE WOULD BE SALT WATER
21. A graduated cylinder is marked into 0.1 mL units. If one measures the precise volume of about 20 mL of liquid,
how many significant figures should be reported?
ALWAYS ESTIMATE ONE DIGIT BEYOND SMALLEST MARKED UNIT – THEREFORE TO NEAREST 0.01. WITH AN
APPROXIMATE 20 mL AMOUNT THE REPORTED NUMBER WOULD BE SOMETHING LIKE 20.00 OR 4 SIG FIGS.
Show all your work for the following exercises. Report your answers in the correct number of significant
figures. You may round atomic weights to the nearest 0.01 g if you wish.
22. Calculate the formula weight of NH4NO3.
80.05 g
23. What is the number of g of oxygen in a 100. gram sample of Calcium Carbonate (CaCO3)?
The formula with of calcium carbonate is 100.09 g = 1 mol
g O = 100g CaCO3 X 1 mol CaCO3/100.09 g CaCO3 X 3 mol O/1 mol CaCO3 X 16.00 g O/1 mol O = 48.0 g
(answer should have 3 sig figs based on 100. Value of 3 sig figs.
24. How many hydrogen atoms are in 1.00 mole of NH4C2H3O2?
There are 7 mol H/1 mol NH4C2H3O2
Therefore
Atoms of H = 1 mol NH4C2H3O2 X 7 mol H/1 mol NH4C2H3O2 X 6.022 X 1023 atoms/mol = 4.21 X 1024 atoms H
25. Do the following calculation, and express the answer using scientific notation.
(3.1 X 105) X (7.768 X 10-7) ANSWER SHOULD HAVE 2 SIG FIGS BASED ON 3.1 NUMBER.
2.4 x 10-1
PERCENT GRADE WAS DETERMINED BY DIVIDING ACTUAL POINTS BY TOTAL POINTS (31)
Class average = 84