Question 1

Gallium has an atomic mass of 69.723 u. The abundance of Ga-69 (68.926 u) is 60.11%. What is the atomic mass, in u, of the other isotope?
A) 70.92 u
B) 70.93 u
C) 70.94 u
D) 70.91 u
E) 70.930 u

Accepted Answer

The answer of Gallium has an atomic mass of 69.723...

Question 2

Cerium has four stable isotopes listed below. If the weighted average atomic mass of cerium is 140.116 u, calculate the atomic mass of cerium-142. 
Ce-136 135.90714 u 0.19%
Ce-138 137.90599 u 0.25%
Ce-140 139.90543 u 88.43%
Ce-142 11.13%
A) 141.911 u
B) 142.617 u
C) 140.334 u
D) 142.501 u
E) 139.886 u

Accepted Answer

To find the atomic mass of cerium-142, use the weighted average formula: (135.90714 * 0.0019) + (137.90599 * 0.0025) + (139.90543 * 0.8843) + (x * 0.1113) = 140.116. Solving for x gives approximately 141.911 u.

Question 3

What is the atomic number for tin?
A) 47.87
B) 50
C) 118.71
D) 22

Accepted Answer

Tin has an atomic number of 50, which corresponds to the number of protons in its nucleus. Choice A (47.87) and D (22) are incorrect, as they correspond to the atomic numbers of silver and titanium, respectively. Choice C (118.71) is incorrect, as it is above the currently known periodic table range of 1-118.

Question 4

Identify the number of neutrons in P^-3. Phosphorus has one stable isotope, phosphorus-31. A) 18 B) 12 C) 19 D) 15 E) 16

Accepted Answer

Phosphorus-31 has an atomic number of 15, meaning it has 15 protons. The mass number is 31, so the number of neutrons is 31 - 15 = 16. The charge of the ion does not affect the number of neutrons.

Question 5

Calculate the atomic mass of chromium if chromium has four naturally occurring isotopes with the following masses and natural abundances: 
Cr-50 49.9461 u 4.35%
Cr-52 51.9405 u 83.79%
Cr-53 52.9407 u 9.50%
Cr-54 53.9389 u 2.36%
A) 51.94 u
B) 51.69 u
C) 208.7 u
D) 53.21 u
E) 52.00 u

Accepted Answer

The answer of Calculate the atomic mass of chromium if...

Question 6

Identify the largest by size atom or ion of carbon. A) p⁺ = 6 n° = 6 e^- = 6 B) p⁺ = 6 n° = 7 e^- = 6 C) p⁺ = 6 n° = 6 e^- = 7 D) p⁺ = 6 n° = 6 e^- = 5

Accepted Answer

The ion with the most electrons (C^-) will have the largest size due to increased electron-electron repulsion and less effective nuclear charge per electron.

Question 7

Carbon has two naturally occurring isotopes, carbon-12 and carbon-13. The more common isotope of carbon is carbon-12 with an abundance of 98.93% while carbon-13 has an atomic mass of 13.00335 u. Calculate the atomic mass of carbon-12 if the atomic mass of carbon is 12.0107 u.
A) 13.1 u
B) 13.0 u
C) 12.0 u
D) 12.8 u
E) 12.4 u

Accepted Answer

Since carbon-12 has an abundance of 98.93%, it means that only 1.07% of carbon must be carbon-13. Therefore, to calculate the atomic mass of carbon-12, we can use the following formula:

Atomic mass of carbon-12 = (0.9893 x atomic mass of carbon-12) + (0.0107 x atomic mass of carbon-13)

Substituting the given values, we get:

atomic mass of carbon-12 = (0.9893 x 12.0107 u) + (0.0107 x 13.00335 u)

atomic mass of carbon-12 = 11.873 u + 0.139 u

atomic mass of carbon-12 = 12.012 u

Therefore, the atomic mass of carbon-12 is 12.012 u, which is closest to choice C (12.0 u).

Question 8

What is the atomic mass for cadmium?
A) 48
B) 112.41
C) 40.08
D) 20

Accepted Answer

The atomic mass for cadmium is 112.41 as given in the periodic table. The other options (A, C, D) are the atomic masses of other elements (selenium, calcium, and calcium again, respectively) and are not related to cadmium's atomic mass.

Question 9

Calculate the atomic mass of gallium if gallium has two naturally occurring isotopes with the following masses and natural abundances: 
Ga-69 68.9256 u 60.11%
Ga-71 70.9247 u 39.89%
A) 69.72 u
B) 69.93 u
C) 70.00 u
D) 69.80 u
E) 70.68 u

Accepted Answer

The atomic mass is calculated by multiplying the mass of each isotope by its natural abundance and summing the results: (68.9256 u * 0.6011) + (70.9247 u * 0.3989) = 69.72 u.

Question 10

Predict the charge that an ion formed from sulfur would have.
A) 1-
B) 6+
C) 3-
D) 4+
E) 2-

Accepted Answer

Sulfur has six valence electrons, and therefore tends to gain two electrons to achieve a full octet. This would result in a charge of -2, making the ion S2-.

Question 11

What is the atomic mass for tin?
A) 47.87
B) 50
C) 118.71
D) 22

Accepted Answer

The atomic mass of tin (Sn) is approximately 118.71 amu (atomic mass units).

Question 12

Identify the number of electrons in P^-3. A) 18 B) 12 C) 19 D) 15 E) 16

Accepted Answer

Phosphorus (P) has an atomic number of 15, meaning it has 15 protons and, in its neutral state, 15 electrons. The P^-3 ion has gained 3 additional electrons, resulting in a total of 18 electrons.

Question 13

Silver has an atomic mass of 107.868 u. The Ag-109 isotope (108.905 u) has an abundance of 48.161%. What is the atomic mass, in u, of the other isotope?
A) 106.905 u
B) 106.908 u
C) 106.903 u
D) 106.911 u

Accepted Answer

The answer of Silver has an atomic mass of 107.868...

Question 14

Bromine has two naturally occurring isotopes, Br-79 and Br-81. The mass of Br-79 is 78.92 u with a percent abundance of 50.69%. If the atomic mass of bromine is 79.904 u, calculate the mass and percent abundance of Br-81.
A) 80.916 u and 50.69%
B) 78.921 u and 49.31%
C) 79.904 u and 49.31%
D) 80.916 u and 49.31%
E) 80.028 u and 50.31%

Accepted Answer

We know that the atomic mass of bromine, which takes into account the percent abundance of each isotope, is 79.904 u. We can set up the following equation to solve for the percent abundance of Br-81:

(0.5069)(78.92 u) + (x)(molar mass of Br-81) = 79.904 u

Solving for x, we get:

x = (79.904 u - 39.963 u) / 80.916 u

x = 0.4931 or 49.31%

Therefore, the mass and percent abundance of Br-81 are 80.916 u and 49.31%, respectively. The answer is choice D.

Question 15

Calculate the atomic mass of silver if silver has two naturally occurring isotopes with the following masses and natural abundances: 
Ag-107 106.90509 u 51.84%
Ag-109 108.90476 u 48.46%
A) 107.90 u
B) 108.00 u
C) 107.79 u
D) 108.32 u
E) 108.19 u

Accepted Answer

The answer of Calculate the atomic mass of silver if...

Question 16

Calculate the atomic mass of tungsten given the atomic mass and percent abundance for the following isotopes: 
W-180 179.9467 u 0.12%
W-182 181.9482 u 26.50%
W-183 182.9502 u 14.31%
W-184 183.9509 u 30.64%
W-186 185.9544 u 28.43%
A) 183.75 u
B) 183.84 u
C) 182.98 u
D) 184.41 u
E) 183.92 u

Accepted Answer

The atomic mass is calculated by multiplying the mass of each isotope by its percent abundance (converted to a decimal), then summing these values: (179.9467 * 0.0012) + (181.9482 * 0.2650) + (182.9502 * 0.1431) + (183.9509 * 0.3064) + (185.9544 * 0.2843) = 183.84 u.

Question 17

Bromine has two naturally occurring isotopes, Br-79 and Br-81. The atomic mass of Br-79 is 78.9183 u with a percent abundance of 50.69% and the atomic mass of Br-81 is 80.9163 u. Calculate the atomic mass of bromine.
A) 80.91 u
B) 78.92 u
C) 79.90 u
D) 80.92 u
E) 80.03 u

Accepted Answer

The atomic mass of bromine is calculated using the weighted average of its isotopes: (78.9183 u * 0.5069) + (80.9163 u * 0.4931) = 79.90 u.

Question 18

Zinc has five naturally occurring isotopes, Zn-64, Zn-66, Zn-67, Zn-68 and Zn-70. Calculate the atomic mass of zinc given the following abundances and atomic masses for the isotopes: 
Zn-64 63.9291 u 48.61%
Zn-66 65.9260 u 27.9%
Zn-67 66.9271 u 4.1%
Zn-68 67.9248 u 18.75%
Zn-70 69.9253 u 0.62%
A) 66.3 u
B) 65.4 u
C) 66.7 u
D) 65.1 u
E) 64.8 u

Accepted Answer

The answer of Zinc has five naturally occurring isotopes, Zn-64,...

Question 19

Predict the charge that an ion formed from bromine would have.
A) 1-
B) 2+
C) 1+
D) 4+
E) 2-

Accepted Answer

Bromine is a halogen and typically gains one electron to achieve a stable electron configuration, resulting in a 1- charge.

Question 20

Identify the number of protons in P^-3. A) 18 B) 12 C) 19 D) 15 E) 16

Accepted Answer

The element P (phosphorus) has an atomic number of 15, which means it has 15 protons. The charge of -3 indicates an excess of electrons, not a change in the number of protons.

Quiz 2: Atoms and Elements

Gallium has an atomic mass of 69.723 u. The abundance of Ga-69 (68.926 u) is 60.11%. What is the atomic mass, in u, of the other isotope?

Cerium has four stable isotopes listed below. If the weighted average atomic mass of cerium is 140.116 u, calculate the atomic mass of cerium-142. Ce-136 135.90714 u 0.19% Ce-138 137.90599 u 0.25% Ce-140 139.90543 u 88.43% Ce-142 11.13%

What is the atomic number for tin?

Identify the number of neutrons in P-3. Phosphorus has one stable isotope, phosphorus-31.

Calculate the atomic mass of chromium if chromium has four naturally occurring isotopes with the following masses and natural abundances: Cr-50 49.9461 u 4.35% Cr-52 51.9405 u 83.79% Cr-53 52.9407 u 9.50% Cr-54 53.9389 u 2.36%

Identify the largest by size atom or ion of carbon.

Carbon has two naturally occurring isotopes, carbon-12 and carbon-13. The more common isotope of carbon is carbon-12 with an abundance of 98.93% while carbon-13 has an atomic mass of 13.00335 u. Calculate the atomic mass of carbon-12 if the atomic mass of carbon is 12.0107 u.

What is the atomic mass for cadmium?

Calculate the atomic mass of gallium if gallium has two naturally occurring isotopes with the following masses and natural abundances: Ga-69 68.9256 u 60.11% Ga-71 70.9247 u 39.89%

Predict the charge that an ion formed from sulfur would have.

What is the atomic mass for tin?

Identify the number of electrons in P-3.

Silver has an atomic mass of 107.868 u. The Ag-109 isotope (108.905 u) has an abundance of 48.161%. What is the atomic mass, in u, of the other isotope?

Bromine has two naturally occurring isotopes, Br-79 and Br-81. The mass of Br-79 is 78.92 u with a percent abundance of 50.69%. If the atomic mass of bromine is 79.904 u, calculate the mass and percent abundance of Br-81.

Calculate the atomic mass of silver if silver has two naturally occurring isotopes with the following masses and natural abundances: Ag-107 106.90509 u 51.84% Ag-109 108.90476 u 48.46%

Calculate the atomic mass of tungsten given the atomic mass and percent abundance for the following isotopes: W-180 179.9467 u 0.12% W-182 181.9482 u 26.50% W-183 182.9502 u 14.31% W-184 183.9509 u 30.64% W-186 185.9544 u 28.43%

Bromine has two naturally occurring isotopes, Br-79 and Br-81. The atomic mass of Br-79 is 78.9183 u with a percent abundance of 50.69% and the atomic mass of Br-81 is 80.9163 u. Calculate the atomic mass of bromine.

Zinc has five naturally occurring isotopes, Zn-64, Zn-66, Zn-67, Zn-68 and Zn-70. Calculate the atomic mass of zinc given the following abundances and atomic masses for the isotopes: Zn-64 63.9291 u 48.61% Zn-66 65.9260 u 27.9% Zn-67 66.9271 u 4.1% Zn-68 67.9248 u 18.75% Zn-70 69.9253 u 0.62%

Predict the charge that an ion formed from bromine would have.

Identify the number of protons in P-3.

Identify the number of neutrons in P^-3. Phosphorus has one stable isotope, phosphorus-31.

Identify the number of electrons in P^-3.

Identify the number of protons in P^-3.