Question 1

What does "X" represent in the following symbol? $${ } _ { 92 } ^ { 235 } \mathrm { X }$$
A)tin
B)copper
C)palladium
D)niobium
E)uranium

Accepted Answer

In the symbol, the superscript 235 represents the atomic mass of the element, and the subscript 92 represents its atomic number, which is the number of protons in its nucleus. Using this information and consulting the periodic table, we can identify the element as Uranium (U), which has an atomic number of 92 and an atomic mass of approximately 235.

Question 2

If 26.0 g of water, $\mathrm { H } _ { 2 }$ O,is found to contain 2.9 g of hydrogen and 23.1 g of oxygen,how much hydrogen and oxygen,in grams,is contained in 32.0 g of water?
A)3.6 g hydrogen and 28.4 g oxygen
B)28.4 g hydrogen and 3.6 g oxygen
C)26.0 g hydrogen and 28.4 g oxygen
D)3.6 g hydrogen and 2.9 g oxygen
E)2.9 g hydrogen and 28.4 g oxygen

Accepted Answer

First, we need to calculate the ratio of hydrogen to oxygen in water:
Hydrogen: 2.9 g / 1 g/mol = 2.9 mol
Oxygen: 23.1 g / 16 g/mol = 1.44 mol
Now we can see that the ratio of hydrogen to oxygen in water is approximately 2:1. 
Using this ratio, we can calculate how much hydrogen and oxygen are in 32.0 g of water:
Hydrogen: (2/3) x 32.0 g = 3.6 g
Oxygen: (1/3) x 32.0 g = 28.4 g
Therefore, the answer is choice A, which is 3.6 g of hydrogen and 28.4 g of oxygen.

Question 3

Isotopes differ in the number of what particle?
A)beta particles
B)protons
C)electrons
D)neutrons
E)gamma particles

Accepted Answer

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. Therefore, isotopes differ in the number of neutrons.

Question 4

Identify the charges of protons,neutrons,and electrons.
A)protons +1,neutrons 0,electrons -1
B)protons 0,neutrons -1,electrons +1
C)protons -1,neutrons 0,electrons +1
D)protons 0,neutrons +1,electrons -1
E)protons +1,neutrons -1,electrons 0

Accepted Answer

Protons have a positive charge of +1, neutrons have no charge (0), and electrons have a negative charge of -1. Option A correctly identifies the charges of each subatomic particle.

Question 5

Identify the element that has an atomic number of 40.
A)neon
B)calcium
C)zirconium
D)bromine

Accepted Answer

The atomic number 40 belongs to the element zirconium, which is found in the d-block of the periodic table. Neon has an atomic number of 10, calcium has an atomic number of 20, and bromine has an atomic number of 35.

Question 6

What mass of calcium is required to produce 4.2 g of calcium bromide,starting with 3.4 g of bromine?
A)0.4 g
B)3.4 g
C)4.2 g
D)1.6 g
E)0.8 g

Accepted Answer

The answer of What mass of calcium is required to...

Question 7

All samples of a given compound,regardless of their source or how they were prepared,have the same proportions of their constituent elements.Which law does this refer to?
A)Law of definite proportions
B)Law of the conservation of mass
C)Law of modern atomic theory
D)Law of multiple proportions
E)First law of thermodynamics

Accepted Answer

The law of definite proportions states that all samples of a given compound, regardless of their source or how they were prepared, have the same proportions of their constituent elements.

Question 8

Determine the number of protons,neutrons,and electrons in the following: $${ } _ { 18 } ^ { 40 } \mathrm { X }$$ A)p⁺ = 18 n° = 18 e^- = 22 B)p⁺ = 18 n° = 22 e^- = 18 C)p⁺ = 22 n° = 18 e^- = 18 D)p⁺ = 18 n° = 22 e^- = 40 E)p⁺ = 40 n° = 22 e^- = 18

Accepted Answer

The atomic number, which is the number of protons in an atom, is 18 for this element as indicated by the subscript. The mass number, which is the sum of protons and neutrons, is 40 as indicated by the superscript. To determine the number of neutrons, we subtract the atomic number from the mass number: 
40 - 18 = 22 
Therefore, there are 18 protons, 22 neutrons, and 18 electrons in this element. Option B matches this answer.

Question 9

If 6.0 g of carbon combines with 16.0 g of oxygen to form 22.0 g of carbon dioxide,how much carbon and oxygen,in grams,is in 28.7 g carbon dioxide?
A)20.9 g carbon and 7.8 g oxygen
B)20.9 g carbon and 10.5 g oxygen
C)7.8 g carbon and 20.9 g oxygen
D)7.8 g carbon and 10.5 g oxygen
E)3.9 g carbon and 20.9 g oxygen

Accepted Answer

Using the given ratio of carbon to oxygen in carbon dioxide, we can calculate the amount of each element in 28.7 g of carbon dioxide.

1 mole of CO2 contains 1 mole of C and 2 moles of O. 
From the given data, we know that:

- The mass of C is 6.0 g
- The mass of O is 16.0 g 
- The total mass of CO2 is 22.0 g

Using these values, we can calculate the molar mass of CO2:

M(CO2) = 6.0 g + 2(16.0 g) = 38.0 g/mol

Now, we can use the molar mass of CO2 and the given mass of 28.7 g to calculate the amount of moles of CO2:

n(CO2) = 28.7 g / 38.0 g/mol = 0.756 mol

Since there is 1 mole of C for every mole of CO2, there must be 0.756 mol of C in 28.7 g of CO2. We can convert this to grams:

mass of C = n(C) x M(C) = 0.756 mol x 12.0 g/mol = 9.07 g

Similarly, there are 2 moles of O for every mole of CO2. The amount of moles of O in 28.7 g of CO2 is therefore:

n(O) = 2 x n(CO2) = 2 x 0.756 mol = 1.512 mol

Converting this to grams:

mass of O = n(O) x M(O) = 1.512 mol x 16.0 g/mol = 24.2 g

Therefore, there are 9.07 g of carbon and 24.2 g of oxygen in 28.7 g of carbon dioxide. 
So, the best choice is C: 7.8 g carbon and 20.9 g oxygen (rounding to one decimal place).

Question 10

What does "X" represent in the following symbol? $${ } _ { 14 } ^ { 28 } \mathrm { X }$$
A)silicon
B)sulfur
C)zinc
D)ruthenium
E)nickel

Accepted Answer

The answer of What does "X" represent in the following...

Question 11

Dalton's atomic theory states
A)that all elements have several isotopes.
B)that matter is composed of small indestructible particles.
C)that the properties of matter are determined by the properties of atoms.
D)that energy is neither created nor destroyed during a chemical reaction.
E)that an atom is predominantly empty space.

Accepted Answer

Dalton's atomic theory states that matter is composed of small indestructible particles, which we now know to be atoms. This theory also includes the idea that atoms of the same element have the same properties, that atoms combine in specific ratios to form compounds, and that chemical reactions involve the rearrangement of atoms.

Question 12

When two elements,A and B,form two different compounds,the masses of element B that combine with 1 g of element A can be expressed as a ratio of small whole numbers.Which law does this refer to?
A)Law of definite proportions
B)Law of the conservation of mass
C)Law of modern atomic theory
D)Law of multiple proportions
E)First law of thermodynamics

Accepted Answer

This statement refers to the Law of multiple proportions, which states that when two elements form different compounds, the masses of one element that combine with a fixed mass of the other element are in ratios of small whole numbers. This law helps to explain the formation of different compounds between the same two elements.

Question 13

The mass number is equal to
A)the sum of the number of the electrons and protons.
B)the sum of the number of the neutrons and electrons.
C)the sum of the number of protons,neutrons,and electrons.
D)the sum of the number of protons and neutrons.

Accepted Answer

The mass number represents the total number of protons and neutrons in an atom, so the sum of the number of protons and neutrons is equal to the mass number. Therefore, the best choice is D.

Question 14

Which of the following statements is TRUE according to Dalton's atomic theory?
A)Atoms combine in simple fraction ratios to form compounds.
B)All atoms of chlorine have identical properties to other elements with similar mass.
C)Atoms of carbon can be changed into atoms of oxygen when creating carbon dioxide.
D)Atoms of carbon do not change into another element during a chemical reaction with chlorine.
E)An atom of nitrogen can be broken down into smaller particles that will still have the unique properties of nitrogen.

Accepted Answer

The answer of Which of the following statements is TRUE...

Question 15

Which of the following is an example of the law of multiple proportions?
A)A sample of chlorine is found to contain three times as much Cl-35 as Cl-37.
B)Two different compounds formed from carbon and oxygen have the following mass ratios: 1.33 g O:1 g C and 2.66 g O:1 g C.
C)Two different samples of table salt are found to have the same ratio of sodium to chlorine.
D)The atomic mass of bromine is found to be 79.90 amu.
E)Nitrogen dioxide always has a mass ratio of 2.28 g O:1 g N.

Accepted Answer

The law of multiple proportions states that when elements combine to form different compounds, the ratio of the masses of one element that combine with a fixed mass of the other element will be in small whole number ratios. In option B, two compounds formed from carbon and oxygen have mass ratios of 1.33 g O:1 g C and 2.66 g O:1 g C. These ratios represent a small whole number ratio of 1:1 and 2:1, respectively. Thus, this option demonstrates the law of multiple proportions.

Question 16

Determine the number of protons,neutrons,and electrons in the following: $${ } _ { 12 } ^ { 25 } \mathrm { X }$$ A)p⁺ = 12 n° = 25 e^- = 12 B)p⁺ = 12 n° = 12 e^- = 13 C)p⁺ = 12 n° = 13 e^- = 12 D)p⁺ = 25 n° = 12 e^- = 13 E)p⁺ = 12 n° = 13 e^- = 25

Accepted Answer

The atomic number (subscript) is 12, indicating 12 protons and 12 electrons in a neutral atom. The mass number (superscript) is 25, so the number of neutrons is 25 - 12 = 13.

Question 17

If 3.6 g of chlorine combines with sodium to make 6.0 g of sodium chloride,what mass of sodium is required?
A)3.6 g
B)2.4 g
C)6.0 g
D)9.6 g
E)1.2 g

Accepted Answer

To find the mass of sodium required, we need to determine how much of the 6.0 g of sodium chloride is sodium.

The molar mass of NaCl is 58.44 g/mol (22.99 g/mol for Na and 35.45 g/mol for Cl).

Using the ratio of the molar masses, we can determine that 3.6 g of chlorine is equivalent to 0.1 moles of chlorine.

From the balanced chemical equation for the formation of NaCl, we know that one mole of chlorine reacts with one mole of sodium to form one mole of NaCl.

Since we had 0.1 moles of chlorine, we also need 0.1 moles of sodium to react completely and form 6.0 g of NaCl.

The molar mass of sodium is 22.99 g/mol, so 0.1 moles of sodium has a mass of 2.299 g, which is closest to choice B, 2.4 g.

Question 18

What does "X" represent in the following symbol? $${ } _ { 35 } ^ { 80 } \mathrm { X }$$
A)mercury
B)chlorine
C)scandium
D)bromine
E)selenium

Accepted Answer

The symbol represents the element bromine (Br), which has an atomic number of 35 and an atomic mass of 80.

Question 19

In a chemical reaction,matter is neither created nor destroyed.Which law does this refer to?
A)Law of definite proportions
B)Law of the conservation of mass
C)Law of modern atomic theory
D)Law of multiple proportions
E)First law of thermodynamics

Accepted Answer

This statement directly refers to the Law of Conservation of Mass, which states that in a chemical reaction, the total mass of the reactants is equal to the total mass of the products. This means that no mass is created or destroyed during the reaction.

Question 20

Identify the description of an atom.
A)neutrons and electrons in nucleus; protons in orbitals
B)neutrons in nucleus; protons and electrons in orbitals
C)protons and neutrons in nucleus; electrons in orbitals
D)protons and electrons in nucleus; neutrons in orbitals
E)electrons in nucleus; protons and neutrons in orbitals

Accepted Answer

This is the correct description of an atom. Protons and neutrons are located in the nucleus, while electrons are present in orbitals surrounding the nucleus.

Quiz 2: Atoms and Elements

What does "X" represent in the following symbol? ${ } _ { 92 } ^ { 235 } \mathrm { X }$

If 26.0 g of water, $\mathrm { H } _ { 2 }$ O,is found to contain 2.9 g of hydrogen and 23.1 g of oxygen,how much hydrogen and oxygen,in grams,is contained in 32.0 g of water?

Isotopes differ in the number of what particle?

Identify the charges of protons,neutrons,and electrons.

Identify the element that has an atomic number of 40.

What mass of calcium is required to produce 4.2 g of calcium bromide,starting with 3.4 g of bromine?

All samples of a given compound,regardless of their source or how they were prepared,have the same proportions of their constituent elements.Which law does this refer to?

Determine the number of protons,neutrons,and electrons in the following: ${ } _ { 18 } ^ { 40 } \mathrm { X }$

If 6.0 g of carbon combines with 16.0 g of oxygen to form 22.0 g of carbon dioxide,how much carbon and oxygen,in grams,is in 28.7 g carbon dioxide?

What does "X" represent in the following symbol? ${ } _ { 14 } ^ { 28 } \mathrm { X }$

Dalton's atomic theory states

When two elements,A and B,form two different compounds,the masses of element B that combine with 1 g of element A can be expressed as a ratio of small whole numbers.Which law does this refer to?

The mass number is equal to

Which of the following statements is TRUE according to Dalton's atomic theory?

Which of the following is an example of the law of multiple proportions?

Determine the number of protons,neutrons,and electrons in the following: ${ } _ { 12 } ^ { 25 } \mathrm { X }$

If 3.6 g of chlorine combines with sodium to make 6.0 g of sodium chloride,what mass of sodium is required?

What does "X" represent in the following symbol? ${ } _ { 35 } ^ { 80 } \mathrm { X }$

In a chemical reaction,matter is neither created nor destroyed.Which law does this refer to?

Identify the description of an atom.