Exam 1 practice problems

Question 1

1. What definition would most accurately define the following statement? The reactivity of
   elements depends on the arrangement of their electrons.
   a) Scientific Theory
   b) Scientific Law
   c) Scientific Hypothesis
   d) Scientific Theorem
   e) Scientific Prognosis

Answer 1

a) Scientific Theory

Question 2

2. Which of the following is true regarding physical properties vs chemical properties?
   a) Flammability is a physical property and observing color is chemical.
   b) Weight is a physical property. Magnetism is chemical.
   c) Flammability and Reactivity are physical properties.
   d) Flammability and Reactivity are chemical. Solubility is physical.

Answer 2

d) Flammability and Reactivity are chemical. Solubility is physical.

Question 3

3. Which of the following is an example of physical change?
   a) Burning wood
   b) Rusting iron
   c) Ice melting into water
   d) Cooking an egg

Answer 3

c) Ice melting into water

Question 4

4. Select all that apply: Example of physical change
   a) Folding of paper
   b) Burning of paper
   c) Breaking of glass
   d) Decaying of plants

Answer 4

a) Folding of paper
c) Breaking of glass

Question 5

5. Which of the following correctly classifies the given substances into elements,
   compounds, and mixtures?
   a) Element: Oxygen (O₂), Compound: Water (H₂O), Mixture: Saltwater
   b) Element: Carbon dioxide (CO₂), Compound: Helium (He), Mixture: Air
   c) Element: Sodium chloride (NaCl), Compound: Hydrogen (H₂), Mixture: Brass
   d) Element: Gold (Au), Compound: Oxygen (O₂), Mixture: Distilled water

Answer 5

a) Element: Oxygen (O₂), Compound: Water (H₂O), Mixture: Saltwater

Question 6

6. The dog’s body has a density of 1.077 g/cm³. An adult K9 displaces 30.2 gallons of
   water upon entering a swimming pool. In pounds, how much does the animal
   weigh?
   a)245 lbs.
   b) 271 lbs.
   c) 282 lbs.
   d) 315 lbs.

Answer 6

b) 271 lbs.

Question 7

A cake recipe calls for 6.02×1023 molecules of sucrose. Given that the molecular
mass of sucrose is 342.295 grams per mole, what would be the density of a single
sucrose molecule if the volume occupied by one molecule is 2.0×10-22 cm³?
a) 1.71 g/cm³
b) 3.42 g/cm³
c) 2.84 g/cm³
d) 7.84 g/cm³

Answer 7

c) 2.84 g/cm³

Question 8

8. Which of the following sets of elements appear in the same family on the periodic
   table?
   a) Sodium (Na), Magnesium (Mg), Aluminum (Al)
   b) Carbon (C), Silicon (Se), Germanium (Ge)
   c) Manganese 2+ (Mn2+), Manganese 3+ (Mn3+), Manganese 5+ (Mn5+)
   d) Nitrogen (14N), Nitrogen (15N), Nitrogen (16N)

Answer 8

b) Carbon (C), Silicon (Se), Germanium (Ge)

Question 9

9. Silver has two naturally occurring isotopes: Silver-107, (107Ag) with an abundance of
   51.84% and Silver-109 (109Ag) with an abundance of 48.16%. If the atomic mass of
   Silver-107 is 106.9051 amu and the atomic mass of Silver-109 is 108.9047 amu, what
   is the average atomic mass of silver? USE CORRECT SIGNIFICANT FIGURES
   a) 107.8770 amu
   b) 107.88 amu
   c) 107.9047 amu
   d) 106.9051 amu
   e) 107.9 amu

Answer 9

b) 107.88 amu

Question 10

11. Which of the following samples contains the LARGEST number of atoms?
    a) 1.72 g of Lithium (Li)
    b) 6.43 g of Sodium (Na)
    c) 10.88 g of Potassium (K)
    d) 19.91 g of Rubidium (Rb)
    e) 33.11 g of Cesium (Cs)

Answer 10

a) 1.72 g of Lithium (Li)

Question 10

10. An unknown element has 79 protons, 118 neutrons, and 76 electrons. Which of the
    following best identifies the element and its ionic state?
    a) Gold-197, Ion with -3 charge
    b) Platinum-197, Ion with +3 charge
    c) Mercury-197, Neutral
    d) Gold-197, Ion with +3 charge
    e) Platinum-195, Neutral

Answer 10

d) Gold-197, Ion with +3 charge

Question 11

12. How many oxygen atoms are in a balloon containing 30 pounds of oxygen (O₂)?
    a) 3.4×1025 atoms
    b) 5.11×1026 atoms
    c) 7.8×1025 atoms
    d) 1.1×1026 atoms
    e) 2.2×1026 atoms

Answer 11

b) 5.11×1026 atoms