Question 1

Bromine is the only nonmetal that is a liquid at room temperature. Consider the isotope bromine-81,  . Select the combination which lists the correct atomic number, neutron number, and mass number, respectively.
A) 35, 46, 81
B) 35, 81, 46
C) 81, 46, 35
D) 46, 81, 35
E) 35, 81, 116

Accepted Answer

The atomic number of bromine, based on its position in the periodic table, is 35. The isotope is bromine-81, which means it has 81 total protons and neutrons. To find the number of neutrons, we subtract the atomic number (35) from the mass number (81), giving us 46 neutrons. Therefore, the correct combination is 35 (atomic number), 46 (neutron number), and 81 (mass number), which is choice A.

Question 2

Who is credited with first measuring the charge of the electron?
A) Dalton
B) Gay-Lussac
C) Thomson
D) Millikan
E) Rutherford

Accepted Answer

Robert Millikan is credited with first measuring the charge of the electron using his famous oil drop experiment in 1909.

Question 3

Kaolinite, a clay mineral with the formula Al₄Si₄O₁₀(OH)₈, is used as a filler in slick-paper for magazines and as a raw material for ceramics. Analysis shows that 14.35 g of kaolinite contains 8.009 g of oxygen. Calculate the mass percent of oxygen in kaolinite. A) 1.792 mass % B) 24.80 mass % C) 30.81 mass % D) 34.12 mass % E) 55.81 mass %

Accepted Answer

E

Question 4

The chemical symbol for potassium is:
A) P
B) Po
C) Pt
D) Pm
E) K

Accepted Answer

The chemical symbol for potassium is K.

Question 5

J. J. Thomson studied cathode ray particles (electrons) and was able to measure the mass/charge ratio. His results showed that
A) the mass/charge ratio varied with as the cathode material was changed.
B) the charge was always a whole-number multiple of some minimum charge.
C) matter included particles much smaller than the atom.
D) atoms contained dense areas of positive charge.
E) atoms are largely empty space.

Accepted Answer

Thomson's discovery of the electron showed that matter included particles much smaller than the atom, which was a major breakthrough in understanding the structure of matter. Option A is not correct because his results showed that the ratio was constant regardless of the cathode material. Option B is incorrect because he did not discover this concept. Option D is incorrect because his experiments did not provide evidence for the existence of dense areas of positive charge in atoms. Option E is not related to Thomson's discovery of the electron.

Question 6

Who is credited with measuring the mass/charge ratio of the electron?
A) Dalton
B) Gay-Lussac
C) Thomson
D) Millikan
E) Rutherford

Accepted Answer

J.J. Thomson is credited with measuring the mass/charge ratio of the electron using his cathode ray tube experiments in the late 1800s. Millikan is credited with determining the charge of the electron through his famous oil drop experiment. Dalton and Gay-Lussac made important contributions to the field of chemistry but did not study electrons. Rutherford is credited with discovering the nucleus of the atom through his gold foil experiment.

Question 7

An isotope of which of the following elements is chosen as a standard in measuring atomic mass?
A) carbon
B) oxygen
C) hydrogen
D) neon
E) helium

Accepted Answer

Carbon-12 is chosen as the standard for measuring atomic mass because it is abundant and stable, making it easy to obtain and measure accurately.

Question 8

Which one of the following statements about atoms and subatomic particles is correct?
A) Rutherford discovered the atomic nucleus by bombarding gold foil with electrons.
B) The proton and the neutron have identical masses.
C) The neutron's mass is equal to that of a proton plus an electron.
D) A neutral atom contains equal numbers of protons and electrons.
E) An atomic nucleus contains equal numbers of protons and neutrons.

Accepted Answer

A neutral atom contains equal numbers of protons and electrons.

Question 9

What are the approximate carbon:hydrogen mass ratios in methane (CH₄) and ethyne (C₂H₂)? A) 1:4 and 1:1 B) 3:2 and 6:1 C) 3:1 and 12:1 D) 3:2 and 12:1 E) 3:1 and 6:1

Accepted Answer

The answer of What are the approximate carbon:hydrogen mass ratios...

Question 10

Lithium forms compounds which are used in dry cells and storage batteries and in high-temperature lubricants. It has two naturally occurring isotopes, ⁶Li (isotopic mass = 6.015121 amu) and ⁷Li (isotopic mass = 7.016003 amu). Lithium has an atomic mass of 6.9409 amu. What is the percent abundance of lithium-6? A) 92.50% B) 86.66% C) 46.16% D) 7.503% E) 6.080%

Accepted Answer

The answer of Lithium forms compounds which are used in...

Question 11

Who is credited with discovering the atomic nucleus?
A) Dalton
B) Gay-Lussac
C) Thomson
D) Millikan
E) Rutherford

Accepted Answer

Ernest Rutherford is credited with discovering the atomic nucleus using his famous gold foil experiment in 1911.

Question 12

When an atom is represented by the symbol  , the value of A is the
A) number of neutrons in the atom.
B) number of protons in the atom.
C) atomic mass of the element.
D) total number of electrons and neutrons in the atom.
E) total number of protons and neutrons in the atom.

Accepted Answer

The answer of When an atom is represented by the...

Question 13

Millikan's oil-drop experiment
A) established the charge on an electron.
B) showed that all oil drops carried the same charge.
C) provided support for the nuclear model of the atom.
D) suggested that some oil drops carried fractional numbers of electrons.
E) suggested the presence of a neutral particle in the atom.

Accepted Answer

Millikan's oil-drop experiment determined the charge on an electron, which is approximately -1.6 x 10^-19 C.

Question 14

Rutherford bombarded gold foil with alpha (a) particles and found that a small percentage of the particles were deflected. Which of the following was not accounted for by the model he proposed for the structure of atoms?
A) the small size of the nucleus
B) the charge on the nucleus
C) the total mass of the atom
D) the existence of protons
E) the presence of electrons outside the nucleus

Accepted Answer

Rutherford's model did not specifically account for the total mass of the atom, as he believed that most of the mass was concentrated in the nucleus. However, later studies showed that the majority of an atom's mass is actually in the form of protons and neutrons in the nucleus, while electrons have very small mass.

Question 15

One amu is defined as A) the mass of a proton. B) 1/12 the mass of an atom of ¹²C. C) the mass of an atom of ¹H. D) 1/20 the mass of an atom of ²⁰Ne. E) 1/16 the mass of an atom of ¹⁶O.

Accepted Answer

One amu is defined as 1/12 the mass of an atom of carbon-12, which is the same as the composition ¹²C. Therefore, choice B is correct. The other choices are incorrect because they do not represent the correct definition of one amu.

Question 16

Silicon, which makes up about 25% of Earth's crust by mass, is used widely in the modern electronics industry. It has three naturally occurring isotopes, ²⁸Si, ²⁹Si, and ³⁰Si. Calculate the atomic mass of silicon. A) 29.2252 amu B) 28.9757 amu C) 28.7260 amu D) 28.0855 amu E) 27.9801 amu

Accepted Answer

To calculate the atomic mass of silicon, we need to take into account the abundance of each isotope and its mass. The given percentages for each isotope are: 
- 28Si: 92.23%
- 29Si: 4.67%
- 30Si: 3.10%

Using these percentages and the respective atomic masses of each isotope (27.9769 amu for 28Si, 28.9765 amu for 29Si, and 29.9738 amu for 30Si), we can calculate the atomic mass of silicon using the formula:

Atomic mass = (% abundance of isotope 1 x atomic mass of isotope 1) + (% abundance of isotope 2 x atomic mass of isotope 2) + (% abundance of isotope 3 x atomic mass of isotope 3)

Substituting the values, we get:

Atomic mass = (0.9223 x 27.9769 amu) + (0.0467 x 28.9765 amu) + (0.0310 x 29.9738 amu)
Atomic mass = 28.0855 amu

Therefore, the atomic mass of silicon is 28.0855 amu, which is closest to choice (D) 28.0855 amu.

Question 17

In a Millikan oil-drop experiment, the charges on several different oil drops were as follows: -5.92; -4.44; -2.96; -8.88. The units are arbitrary. What is the likely value of the electronic charge in these arbitrary units?
A) -1.11
B) -1.48
C) -2.22
D) -2.96
E) -5.55

Accepted Answer

We can use Millikan's equation to solve for the electronic charge (e):

q = ne

where q is the charge on the oil drop and n is the number of electrons on the drop.

To find the electronic charge, we need to look for the smallest common denominator of the charges given. In this case, the smallest common denominator is 0.04, since all the charges are multiples of this.

Now, we can divide each charge by 0.04 to get the number of electrons:

-5.92 / 0.04 = -148
-4.44 / 0.04 = -111
-2.96 / 0.04 = -74
-8.88 / 0.04 = -222

We can see that there is a pattern here: the number of electrons is always a multiple of 37. Therefore, the likely value of the electronic charge is -37 in these arbitrary units.

Checking our answer using one of the charges:

-5.92 = (-37) * (-0.16)

This confirms that the electronic charge is likely -37 in these units.

Finally, we need to convert back to the original units by multiplying by 0.04:

-37 * 0.04 = -1.48

Therefore, the answer is B.

Question 18

Which of the following symbols does not represent an element? A) O₂ B) Co C) HF D) Cs E) Xe

Accepted Answer

HF is not a symbol for an element; it represents hydrofluoric acid, a compound made of hydrogen (H) and fluorine (F).

Question 19

Atoms X, Y, Z, and R have the following nuclear compositions: 
 
Which two are isotopes?
A) X & Y
B) X & R
C) Y & R
D) Z & R
E) X & Z

Accepted Answer

The answer of Atoms X, Y, Z, and R have...

Question 20

. If the compositions of the two compounds are consistent with the law of multiple proportions, which of the following compositions could be that of compound 2?
A) 23.4 mass % A; 76.6 mass % B
B) 30.4 mass % A; 69.6 mass % B
C) 33.3 mass % A; 66.7 mass % B
D) 53.3 mass % A; 46.7 mass % B
E) 73.3 mass % A; 26.7 mass % B

Accepted Answer

The law of multiple proportions states that if two elements form more than one compound, the ratios of the masses of the second element that combine with a fixed mass of the first element will be ratios of small whole numbers. Option B provides a composition that could be consistent with this law when compared to another compound.

Quiz 2: The Components of Matter

Bromine is the only nonmetal that is a liquid at room temperature. Consider the isotope bromine-81, . Select the combination which lists the correct atomic number, neutron number, and mass number, respectively.

Who is credited with first measuring the charge of the electron?

Kaolinite, a clay mineral with the formula Al₄Si₄O₁₀(OH) ₈, is used as a filler in slick-paper for magazines and as a raw material for ceramics. Analysis shows that 14.35 g of kaolinite contains 8.009 g of oxygen. Calculate the mass percent of oxygen in kaolinite.

The chemical symbol for potassium is:

J. J. Thomson studied cathode ray particles (electrons) and was able to measure the mass/charge ratio. His results showed that

Who is credited with measuring the mass/charge ratio of the electron?

An isotope of which of the following elements is chosen as a standard in measuring atomic mass?

Which one of the following statements about atoms and subatomic particles is correct?

What are the approximate carbon:hydrogen mass ratios in methane (CH₄) and ethyne (C₂H₂) ?

Who is credited with discovering the atomic nucleus?

When an atom is represented by the symbol , the value of A is the

Millikan's oil-drop experiment

Rutherford bombarded gold foil with alpha (a) particles and found that a small percentage of the particles were deflected. Which of the following was not accounted for by the model he proposed for the structure of atoms?

One amu is defined as

Silicon, which makes up about 25% of Earth's crust by mass, is used widely in the modern electronics industry. It has three naturally occurring isotopes, ²⁸Si, ²⁹Si, and ³⁰Si. Calculate the atomic mass of silicon.

In a Millikan oil-drop experiment, the charges on several different oil drops were as follows: -5.92; -4.44; -2.96; -8.88. The units are arbitrary. What is the likely value of the electronic charge in these arbitrary units?

Which of the following symbols does not represent an element?

Atoms X, Y, Z, and R have the following nuclear compositions: Which two are isotopes?

. If the compositions of the two compounds are consistent with the law of multiple proportions, which of the following compositions could be that of compound 2?