Question 1

The total number of neutrons in an 192Ir2+ cation is ________.
A) 115
B) 77
C) 192
D) 75
E) 269

Accepted Answer

The atomic number of Ir is 77, so the number of protons in the cation is 77. The mass number of 192Ir is 192, so the number of neutrons in the cation is 192 - 77 = 115.

Question 2

How many atoms of sulfur are in 280 g of a 50% by mass H₂SO₄ solution? A) 8.6 × 10²⁵ atoms B) 8.6 × 10²³ atoms C) 8.0 × 10²⁵atoms D) 8.0 × 10²³ atoms E) 2.8 × 10²⁹ atoms

Accepted Answer

The solution contains 140 g of H₂SO₄ (50% of 280 g). The molar mass of H₂SO₄ is 98 g/mol, so there are 140 g / 98 g/mol = 1.4286 mol of H₂SO₄. Each molecule of H₂SO₄ contains one sulfur atom, so there are 1.4286 mol × 6.022 × 10²³ atoms/mol = 8.6 × 10²³ sulfur atoms.

Question 3

How many atoms of silicon are contained in 8.50 × 10^-5 grams? A) 1.44 × 10²³ atoms B) 1.82 × 10¹⁸ atoms C) 5.02 × 10³⁰ atoms D) 5.02 × 10¹⁸ atoms E) 1.82 × 10²⁰ atoms

Accepted Answer

To find the number of atoms, divide the mass by the molar mass of silicon (28.0855 g/mol) to get moles, then multiply by Avogadro's number (6.022 × 10^23 atoms/mol). This calculation gives approximately 1.82 × 10^18 atoms.

Question 4

A cubic centimeter of lead weighs 11.35 g. How many atoms are in the block? A) 6.8 × 10²⁴ atoms B) 2.4 × 10²³atoms C) 3.3 × 10²² atoms D) 5.3 × 10²² atoms E) 1.1 × 10²⁵ atoms

Accepted Answer

The answer of A cubic centimeter of lead weighs 11.35...

Question 5

How many atoms of rubidium-85 are in 87.2 g of rubidium? Rubidium-85 is 72.2 % abundant. A) 5.16 × 10⁴⁶ atoms B) 4.44 × 10²³ atoms C) 8.51 × 10²³ atoms D) 6.14 × 10²² atoms E) 1.02 × 10²⁴ atoms

Accepted Answer

The answer of How many atoms of rubidium-85 are in...

Question 6

A certain mass of nickel reacts with sulphur to produce 2.83 g of NiS. The same mass of nickel reacts completely with 0.5 g of oxygen to produce 2.33 g of NiO. How many grams of sulfur reacted in the first reaction? A) 0.5 g B) 1 g C) 1.5 g D) 10^-1 g E) 1.25 g

Accepted Answer

The answer of A certain mass of nickel reacts with...

Question 7

A 1.4 g sample of calcium is reacted with 3.2 g of oxygen. The only product after the reaction is 1.96 g of CaO. How many grams of oxygen remains unreacted?
A) 0.56 g
B) 0.224 g
C) 2.64 g
D) 0.264 g
E) 0.203 g

Accepted Answer

The answer of A 1.4 g sample of calcium is...

Question 8

Which is the proper chemical symbol for tungsten?
A) Te
B) Ti
C) Tm
D) W
E) Tc

Accepted Answer

The proper chemical symbol for tungsten is W. This comes from the German word for tungsten, "Wolfram".

Question 9

What mass of magnesium is necessary to make 10.5 g of magnesium bromide if 1.04 g of magnesium makes 7.88 g of magnesium bromide?
A) 1.39 g
B) 79.9 g
C) 1.58 g
D) 3.66 g
E) 7.89 g

Accepted Answer

The mass of magnesium needed is found by setting up a proportion based on the given relationship: $1.04 \, \text{g Mg} : 7.88 \, \text{g MgBr}_2 = x \, \text{g Mg} : 10.5 \, \text{g MgBr}_2$. Solving for $x$ gives $x = \frac{1.04 \times 10.5}{7.88} = 1.39 \, \text{g}$.

Question 10

How many Cu atoms are present in a 75.0 cm length of 20-gauge copper wire? A 20-gauge wire has a diameter of 0.03196 in. Copper's density is 8.92 g/cm3. A) 1.31 × 10²¹ B) 3.28 × 10²² C) 8.08 × 10²¹ D) 1.04 × 10²² E) 2.08 × 10²²

Accepted Answer

First, we need to calculate the volume of the wire:
radius = diameter/2 = 0.01598 in. = 0.04055 cm
V = πr^2h = π(0.04055 cm)^2 (75.0 cm) = 0.382 cm^3

Next, we can use the density of copper to calculate the mass of the wire:
m = DV = (8.92 g/cm^3) (0.382 cm^3) = 3.41 g

Finally, we can use the molar mass of copper to convert the mass to number of atoms:
1 mol Cu = 63.55 g Cu
1 atom Cu = 1 mol Cu/6.022 × 10^23 atoms Cu
n = m/M = (3.41 g)/(63.55 g/mol)/(6.022 × 10^23 atoms/mol) = 3.28 × 10^21 atoms

Therefore, there are 3.28 × 10^21 Cu atoms in the wire.

Question 11

A sample of pure carbon weighing 1.48 g was burned in an excess of air. The mass of carbon dioxide, the sole product, was 5.42 g. In a second experiment, 11.62 g of carbon dioxide was obtained. What mass of carbon was burned in the second experiment?
A) 42.6 g
B) 3.17 g
C) 3.54 g
D) 0.866 g
E) 11.6 g

Accepted Answer

The ratio of carbon to carbon dioxide in the first experiment is 1.48 g C to 5.42 g CO2. Using this ratio, for 11.62 g of CO2, the mass of carbon burned is (1.48/5.42) * 11.62 = 3.17 g.

Question 12

If the density of lead is 11.34 g/cm3, how many atoms are in a piece of lead that is 2.00 cm wide, 1.00 m long, and 2.00 mm thick? A) 1.32 × 10²⁴ atoms B) 1.16 × 10²³ atoms C) 1.32 × 10²³ atoms D) 1.16 × 10²² atoms E) 6.60 × 10²³ atoms

Accepted Answer

The correct answer is A because the density of lead is 11.34 g/cm3, so the mass of the piece of lead is 2.00 cm * 1.00 m * 2.00 mm * 11.34 g/cm3 = 494.96 g. The molar mass of lead is 207.2 g/mol, so the number of moles of lead in the piece is 494.96 g / 207.2 g/mol = 2.39 mol. The number of atoms in the piece is 2.39 mol * 6.022 * 10^23 atoms/mol = 1.44 * 10^24 atoms.

Question 13

How many atoms of lead are required to cover a 33.0 cm by 45.0 cm area with a sheet of lead that is 0.140 mm thick? The density of lead is 11.35 g/cm3. A) 6.86 × 10²³ B) 2.29 × 10²⁶ C) 2.29 × 10²⁵ D) 6.86 × 10²² E) 1.42 × 10²⁶

Accepted Answer

The answer of How many atoms of lead are required...

Question 14

With mass spectral data the ratio of the mass of 14N/12C was found to be 1.167. What is the mass of the 14N atom?
A) 14.017 u
B) 10.292 u
C) 14.004 u
D) 17.000 u
E) 14.007 u

Accepted Answer

The answer of With mass spectral data the ratio of...

Question 15

A 3.214 g sample of magnesium reacts with 8.416 g of bromine. The only product is magnesium bromide. If 1.934 g of magnesium is left unreacted, how much magnesium bromide is formed?
A) 1.280 g
B) 5.202 g
C) 9.696 g
D) 7.136 g
E) 3.268 g

Accepted Answer

The answer of A 3.214 g sample of magnesium reacts...

Question 16

How many moles are represented by 2.5 × 10¹⁵ Na atoms? A) 3.8 × 10^-10 mol B) 1.8 × 10^-10 mol C) 1.5 × 10³⁹ mol D) 4.2 × 10^-9 mol E) 1.1 × 10¹⁴ mol

Accepted Answer

The number of moles of Na atoms can be calculated using Avogadro's number, which is 6.022 × 10²³ atoms/mol. Therefore, 2.5 × 10¹⁵ Na atoms is equal to 2.5 × 10¹⁵ atoms / (6.022 × 10²³ atoms/mol) = 4.2 × 10^-9 mol.

Question 17

57.7 g Ni contains how many atoms? A) 6.13 × 10²³ atoms B) 3.47 × 10²³ atoms C) 5.92 × 10²³ atoms D) 1.24 × 10²⁴ atoms E) 0.983 atoms

Accepted Answer

To calculate the number of atoms in 57.7 g of nickel, we first need to convert grams to moles using the molar mass of nickel:

57.7 g Ni × (1 mol Ni / 58.69 g Ni) = 0.982 mol Ni

Next, we can use Avogadro's number (6.022 × 10^23 atoms/mol) to convert moles to atoms:

0.982 mol Ni × (6.022 × 10^23 atoms/mol) = 5.92 × 10^23 atoms

Therefore, the answer is (C) 5.92 × 10^23 atoms.

Question 18

The natural abundance of calcium in the earth's crust is 3.4% by mass. How many calcium atoms are present in a 1.50 g sample of the earth's crust? A) 6.6 × 10²³ atoms B) 3.1 × 10²² atoms C) 7.7 × 10²⁰ atoms D) 7.7 × 10²² atoms E) 5.1 × 10²⁰ atoms

Accepted Answer

First, calculate the mass of calcium in the sample: 1.50 g * 0.034 = 0.051 g of calcium. Then, convert the mass of calcium to moles: 0.051 g / 40.08 g/mol = 0.001272 moles. Finally, convert moles to atoms using Avogadro's number: 0.001272 moles * 6.022 × 10^23 atoms/mol = 7.7 × 10^20 atoms.

Question 19

How many atoms of hydrogen are present in 1.5 lb of hydrogen peroxide, which is 5.93% hydrogen? (1 lb = 454 grams) A) 2.4 × 10²⁵ atoms B) 1.21 × 10²⁵ atoms C) 1.2 × 10²⁵ atoms D) 2.41 × 10²⁵ atoms E) 1.2 × 10²⁰ atoms

Accepted Answer

1.5 lb of hydrogen peroxide is 681 grams. 5.93% of 681 grams is 40.3 grams of hydrogen. 40.3 grams of hydrogen is 2.41 × 10²⁵ atoms of hydrogen.

Question 20

Write the symbol for the radioactive isotope phosphorus-32.
A) 
B) 
C) 
D) 
E)

Accepted Answer

The answer of Write the symbol for the radioactive isotope...

Quiz 2: Atoms and the Atomic Theory

The total number of neutrons in an 192Ir2+ cation is ________.

How many atoms of sulfur are in 280 g of a 50% by mass H2SO4 solution?

How many atoms of silicon are contained in 8.50 × 10-5 grams?

A cubic centimeter of lead weighs 11.35 g. How many atoms are in the block?

How many atoms of rubidium-85 are in 87.2 g of rubidium? Rubidium-85 is 72.2 % abundant.

A certain mass of nickel reacts with sulphur to produce 2.83 g of NiS. The same mass of nickel reacts completely with 0.5 g of oxygen to produce 2.33 g of NiO. How many grams of sulfur reacted in the first reaction?

A 1.4 g sample of calcium is reacted with 3.2 g of oxygen. The only product after the reaction is 1.96 g of CaO. How many grams of oxygen remains unreacted?

Which is the proper chemical symbol for tungsten?

What mass of magnesium is necessary to make 10.5 g of magnesium bromide if 1.04 g of magnesium makes 7.88 g of magnesium bromide?

How many Cu atoms are present in a 75.0 cm length of 20-gauge copper wire? A 20-gauge wire has a diameter of 0.03196 in. Copper's density is 8.92 g/cm3.

A sample of pure carbon weighing 1.48 g was burned in an excess of air. The mass of carbon dioxide, the sole product, was 5.42 g. In a second experiment, 11.62 g of carbon dioxide was obtained. What mass of carbon was burned in the second experiment?

If the density of lead is 11.34 g/cm3, how many atoms are in a piece of lead that is 2.00 cm wide, 1.00 m long, and 2.00 mm thick?

How many atoms of lead are required to cover a 33.0 cm by 45.0 cm area with a sheet of lead that is 0.140 mm thick? The density of lead is 11.35 g/cm3.

With mass spectral data the ratio of the mass of 14N/12C was found to be 1.167. What is the mass of the 14N atom?

A 3.214 g sample of magnesium reacts with 8.416 g of bromine. The only product is magnesium bromide. If 1.934 g of magnesium is left unreacted, how much magnesium bromide is formed?

How many moles are represented by 2.5 × 1015 Na atoms?

57.7 g Ni contains how many atoms?

The natural abundance of calcium in the earth's crust is 3.4% by mass. How many calcium atoms are present in a 1.50 g sample of the earth's crust?

How many atoms of hydrogen are present in 1.5 lb of hydrogen peroxide, which is 5.93% hydrogen? (1 lb = 454 grams)

Write the symbol for the radioactive isotope phosphorus-32.

How many atoms of sulfur are in 280 g of a 50% by mass H₂SO₄ solution?

How many atoms of silicon are contained in 8.50 × 10^-5 grams?

How many moles are represented by 2.5 × 10¹⁵ Na atoms?