Chem 1405 Test 1
Total Score 50
There are 2 sections to this test.
Section I
Answer all question.
1. Choose the response that includes all the items listed below that are pure substances.
i. orange juice ii. steam iii. ocean water iv. oxygen v. vegetable soup
A) i, iii, v
B) ii, iv
C) iv only
D) i, iii, iv
E) all of them are pure
2. A concise verbal or mathematical statement of a relationship between phenomena that
is always the same under the same conditions is referred to as
A) a hypothesis.
B)a law
C)a theory
D) none of the above.
3. Which is a chemical property of Tin
A) Tin can be hammered into a thin sheet.
B) At –40°C a sheet of tin crumbles to a gray powder.
C) Tin melts at 231.9°C.
D) When a bar of tin is bent, it emits an audible “cry”.
E) Tin erodes when added to hydrochloric acid, and a clear gas forms.
4. In a cathode ray tube
A) electrons pass from the anode to the cathode.
B) electrons pass from the cathode to the anode.
C) protons pass from the anode to the cathode.
D) protons pass from the cathode to the anode.
5. Atoms of the same element with different mass numbers are called
A) Isotopes
B) Ions
C) Neutrons
D) Atomic number
E) Chemical formula
6. Complete the following chart, in order from left to right
Ion
Mass Number
4
Protons
Neutrons
2
Electrons
0
4
A) He, 2
B) 4Be, 4
C) 4Be, 2
D) 4He, 4
E) 2H, 2
7. Which is the correct formula for iron(II) phosphate?
A) Fe2PO4
B) Fe3(PO4)2
C) Fe2PO3
D) Fe(PO3)2
E) Fe(PO4)2
8. Give the correct number of significant figures and units to the problem below
5.46 m3/ 2.01 m2 =
A)2.72 m5
B)2.72 m
C)2.72 m2
D) 2.72 m-1
E) 2.72 m3
9. The element oxygen consists of three naturally occurring isotopes: 16O, 17O, and 18O.
The atomic mass of oxygen is 16.0 amu. What can be implied about the relative
abundances of these isotopes?
A)More than 50% of all O atoms are 17O.
B) Almost all O atoms are 18O.
C) Almost all O atoms are 17O.
D) The isotopes all have the same abundance, i.e. 33.3%.
E) The abundances of 17O and 18O are very small.
10. An average atom of uranium (U) is approximately how many times heavier than an
atom of potassium?
A) 6.1 times
B) 4.8 times
C) 2.4 times
D) 12.5 times
E) 7.7 times
11. Which of the following elements is chemically similar to magnesium?
A) Sulfur
B) Calcium
C) Iron
D) Nickel
E) Potassium
12. Which is the formula for lead(II) chloride?
A) Pb4Cl
B) PbCl2
C) PbCl3
D) PbCl4
E) Pb2Cl4
13. The straight chain hydrocarbon that contains seven carbon atoms is
A) propane
B) butane
C) hexane
D) heptane
E) ethane
14. One mole of iron
A) is heavier than one mole of lead (Pb).
B) is 77.0 g of iron.
C) is 26.0 g of iron.
D) weighs the same as one mole of lead.
E) None of the above.
15. The SI prefixes kilo and milli represent, respectively:
A) 10–9 and 10–6.
B) 106 and 10–3.
C) 103 and 10–3.
D) 109 and 10–6.
E) 10–9 and 10–1.
Section II
Answer all questions.
Show all the steps in your calculations to get all the points for each
question
16. Formaldehyde has the formula HCHO. How many molecules are there in 0.11 g of
formaldehyde? 3
NA =6.023 X 10 23
17 The percent composition by mass of an unknown chlorinated hydrocarbon was found
to be 37.83% C, 6.35% H, and 55.83% Cl by mass. What is the empirical formula of this
compound? 5
18. Lead melts at 601.0°C. What temperature is this in °F?
3
19A. The bond formed between a metal and a nonmetal is usually a(n) _________ bond.
B. The bond formed between a nonmetal and a nonmetal is usually a(n) _________ bond.
C. The bond formed between water molecules is called _____________________bond.
D. Classify the following as ionic or covalent, polar or non polar compounds:
i.NaI
ii.C6H6
iii. CH3COOH
iv. C6H12O6
20a What is ammonia and ammonium ion, in that order? 1X2
20b. What is the formula for xenon difluoride?
1
.5X4
20c. What is the formula for dibromine heptoxide?
1
21. Define the following:
A. What is electronegativity? How does the electronegativity vary among metals and non
metal?
2
B.Calculate the density(in g/cm3) of a cube of copper whose length is 4mm and weighs
2oz
(1oz-30g)
2
C. Predict the structure of H2O with your knowledge of bonding an dnon-bonding
electrons
2
22 The following question are based on metallic element in Group III
a It would form an ion by losing three electrons: 1
22b. Give the electronic configuration of this element and its cation:
2X1
22c. This element reacts with molecular oxygen in air to form this stable layer which
prevents further reaction of this element with air. Hence it is superior to Iron as a building
material at seaside locations where rusting weakens the structure of iron based materials.
Show the oxides of this element and iron with molecular oxygen, assuming the highest
valence states for both the unknown(III) and iron(III): 2X1
22d. Write the Lewis structure for these two metal oxides, including the lone pairs of
electrons where relevant:
2X2
Bonus question
10:
a. How do atoms behave in an electric field?
b. What is magnetism? How are atoms affected by a magnetic field?
c. Define Dipole moment of molecule? How is dipole moment related to magnetism?
d.Dipole moment is a vector quantity. What is a vector quantity?
e. Based on the information above, classify the following astoms as possessing
magnetism or resultant dipole movement: Hint: for I and ii write the electronic
configuration
i. Fe
ii. Mn
Hint: Write the Lewis structure with lone pairs of electrons and consider the
electronegativities of the atoms
iii. NH3
iv. CHCl3.