Deck 1: The Atom in Modern Chemistry

Question 1

Air is best classified as

A) an element
B) a compound
C) a homogeneous mixture
D) a heterogeneous mixture

Answer 1

C

Question 2

A marble tabletop is best classified as

A) an element
B) a compound
C) a homogeneous mixture
D) a heterogeneous mixture

Answer 2

D

Question 3

A pure substance that is composed of only one type of atom is best classified as

A) an element
B) a compound
C) a homogeneous mixture
D) a heterogeneous mixture

Answer 3

A

Question 4

Which statement best describes N₂

A) it is an element
B) it is a compound
C) it is a homogeneous mixture
D) it is a heterogeneous mixture
E) both a & b

Question 5

A clear liquid is placed into a beaker and heated until it boils. After all of the liquid has evaporated, a white powder is found in the beaker. The original liquid is best classified as

A) an element
B) a compound
C) a homogeneous mixture
D) a heterogeneous mixture

Question 6

A red solid is heated in an evacuated container until it completely vaporizes. When the vapor cools, it is found to be a sliver liquid. The mass of the silver liquid is less than that of the original solid. The red solid is best classified as

A) an element
B) a compound
C) a homogeneous mixture
D) a heterogeneous mixture

Question 7

A sample of carotene is extracted from a carrot and found to contain 17.9 g of carbon and 2.1 g of hydrogen. A second carotene sample is synthesized in the lab and found to contain 10.0 g of carbon. How many grams of hydrogen are in the second sample?

A) 0.021 g
B) 0.940 g
C) 1.17 g
D) 2.00 g
E) 3.76 g

Question 8

Sodium chloride that is formed from a reaction of sodium vapor and chlorine gas is found to be 39.34% sodium by mass. A 4.86 g sample of sodium chloride that is purified from sea water contains how many grams of sodium?

A) 0.980 g
B) 1.91 g
C) 2.95 g
D) 4.46 g
E) there is no way to know because the compound is derived from a different source

Question 9

Two elements X and Y combine to form two compounds with the following compositions If compound 1 has the formula XY₃ then a possible formula for compound 2 is

A) XY₂
B) X₂Y₅
C) XY₄
D) X₂Yl₉
E) XY₅

Question 10

A compound is found to be 40.62% Si and 59.94% N. A possible formula for this compound is

A) Si₂N
B) SiN₂
C) SiN₃
D) Si₂N₆
E) SiN₃ and Si₂N₆ are both possible

Question 11

You are trying to use percent mass of hydrogen to determine if a compound is epinephrine (C₉H₁₃NO₃) or nor-epinephrine (C₈H₁₁NO₃). What is the maximum error that is acceptable for your instrument in order to distinguish between these two compounds?

A) °0.5%
B) °1%
C) °2%
D) °5%
E) °10%

Question 12

A 20.0 g a sample is composed of a mixture of Fe₂O₃ and Fe₃O₄. The mixture is found to contain 14.45 g of iron. What percent of the sample is Fe₂O₃?

A) 2%
B) 22%
C) 50%
D) 72%
E) 98%

Question 13

In the presence of a catalyst carbon monoxide (CO) will reaction with oxygen (O₂) to form carbon dioxide (CO₂). How many liters of carbon dioxide can be formed from 1.5 L of carbon monoxide (with excess oxygen) if all the gases are held at the same temperature and pressure?

A) 0.15 L
B) 0.5 L
C) 0.75 L
D) 1.5 L
E) 3.0 L

Question 14

Gibbsite is an aluminum ore that is composed of 34.59% Al, 3.88% H, and 61.53% O. How much aluminum can be refined from 248.0 g of Gibbsite?

A) 7.09 g
B) 22.81 g
C) 45.59 g
D) 85.78 g
E) 152.6 g

Question 15

1.28 g of pure gold reacts with chlorine gas to produce 1.97 g of a red solid. A possible formula for the red solid is?

A) Au₂Cl
B) AuCl
C) AuCl₂
D) Au₂Cl₅
E) Au₂Cl₆

Question 16

Methane gas (CH₄) reacts with oxygen (O₂) to produce water vapor and carbon dioxide. What volume of water (H₂O) and carbon dioxide (CO₂) will be formed from the complete reaction of 3 L of methane with oxygen if all the gases are held at the same temperature and pressure?

A) 3 L of H₂O and 3 L of CO₂
B) 6 L of H₂O and 3 L of CO₂
C) 3 L of H₂O and 6 L of CO₂
D) 6 L of H₂O and 6 L of CO₂
E) 3 L of H₂O and 1.5 L of CO₂

Question 17

The element zinc has two naturally occurring isotopes. The natural abundances and isotopic masses are The atomic mass of naturally occurring zinc is

A) 112.990
B) 113.582
C) 113.904
D) 114.582
E) 114.818

Question 18

The element antinomy has two naturally occurring isotopes. The natural abundances and isotopic masses are The atomic mass of naturally occurring antinomy is

A) 121.760
B) 121.904
C) 122.048
D) 122.904
E) 124.048

Question 19

How many neutrons are in a nucleus of a ²³⁵U atom?

A) 51
B) 92
C) 143
D) 194
E) 235

Question 20

Which has the greatest number of neutrons?

A) ²³⁸U
B) ²³⁷Np
C) ²³⁹Pu
D) ²⁴⁰Am
E) ²⁴⁰Cm

Question 21

Which has the same number of neutrons as protons?

A) ¹H
B) ¹⁹F
C) ³²S
D) ⁴⁰Ar
E) ⁸⁰Se

Question 22

In Millikan's oil drop experiment, he was able to determine the charge of the electron because

A) each oil drop had only one electron
B) each oil drop contained an integer number of electrons
C) each oil drop had an identical charge
D) the oil drops were too small to be affected by gravity
E) the oil drops all fell at a constant speed

Question 23

In Rutherford's experiment scattering a particles off gold foil he

A) observed that a small fraction of the a particles were negatively charged.
B) observed that most of the a particles pass straight through the foil.
C) observed that a small fraction of the a particles scattered backwards from the foil.
D) both b & c
E) all of the above

Question 24

Naturally occurring silicon is composed of three isotopes: ²⁸Si (atomic mass 27.98), ²⁹Si (atomic mass 28.98), and ³⁰Si (atomic mass 29.97). The atomic mass of the naturally occurring isotope mixture is 28.0855. The relative percentages of ²⁸Si, ²⁹Si, and ³⁰Si are

A) 99.7, 0.1, 0.2
B) 92.2, 4.7, 3.1
C) 90.2, 1.3, 8.5
D) 80.2, 10.8, 9.0
E) 50.4, 20.5, 29.1

Question 25

Radon has seventeen isotopes ranging from ²¹⁰Rd to ²²⁶Rd. What do all of these isotopes have in common?

A) the same number of electrons
B) the same number of protons
C) the same number of neutrons
D) a and b
E) b and c

Question 26

What elemental isotope has 51 protons and 72 neutrons?

A) ²¹Ne
B) ⁵¹V
C) ⁷²Ge
D) ¹²³Sb
E) ¹²³Te

Question 27

If the density of the nucleus of gold is approximately 1×10¹⁵ g cm^-3 and solid gold has a density of 19.3 g cm^-3 estimate the percentage of the volume of solid gold that is "occupied" by the nucleus?

A) 2×10^-12 %
B) 2×10^-8 %
C) 2×10^-4 %
D) 2×10^-2 %
E) 2%

Question 28

10.3 g of an unknown compound is sealed in a tube with 25.8 g of hydrochloric acid. The tube is heated the compound completely dissolves. What is the mass of the contents of the tube after the reaction?

A) exactly 36.1 g
B) slightly more than 35.8 g
C) slightly less than 35.8 g
D) exactly 10 g
E) there is no way to know without more information about the reaction

Question 29

In a strange and alternative universe you repeat Millikan's oil drop experiment and measure the following charges on different oil drops Using this give your best estimate for the unit of fundamental charge in this alternative universe

A) 1.2×10^-17 C
B) 1.8×10^-17 C
C) 3.6×10^-17 C
D) 9.0×10^-17 C
E) 1.2×10^-16 C

Question 30

Chlorine has two naturally occurring isotopes ³⁵Cl (atomic mass 34.97) and ³⁷Cl (atomic mass of 36.96). If ions of naturally occurring Cl₂ are detected in a mass spectrometer how many peaks should be observed?

A) one
B) two
C) three
D) four
E) five

Question 31

Which nuclide has more protons than neutrons?

A) Fe
B) Ni
C) K
D) Co

Question 32

Antimony has two naturally occurring isotopes with masses given in the table below. The relative atomic mass given for antimony on the periodic table is 121.75. Which of the following is true?

A) When a sample of antimony is placed in a mass spectrometer, one peak will be observed at the average relative atomic mass.
B) Two peaks will be observed and the ¹²¹Sb will be larger.
C) Two peaks will be observed and the ¹²³Sb will be larger.
D) Three peaks will be observed at 120.9038, 121.75, and 122.90911.
E) Not enough information is given to answer the problem.

Question 33

Distillation can be used to separate single phase solutions that are:

A) Compounds of different elements
B) Homogeneous mixtures of different compounds
C) Composed of elemental isotopes
D) Substances of different compounds
E) None of the above