Question 1

Which of the following pairs of compounds can be used to illustrate the law of multiple proportions?

Accepted Answer

The law of multiple proportions states that when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other are in the ratio of small whole numbers. NO and NO₂ illustrate this as they are both compounds of nitrogen and oxygen, with different ratios of oxygen to nitrogen.

Question 2

Which are alkaline earth halides?

Accepted Answer

Alkaline earth metals are the elements in the second group of the periodic table, including Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra). Halides are the compounds formed by these elements with the halogen series of elements, including Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), and Astatine (At). Therefore, the alkaline earth halides are the compounds formed by the alkaline earth metals with one of the halogen elements. Option C includes CaF2, MgBr2, and SrI2, which are all alkaline earth halides. Option A includes oxides and sulfides of Mg and Ca, which are not halides. Option B includes halides of alkali metals, such as Na and K, which are not alkaline earth metals. Option D includes compounds that are not halides but contain aluminum (Al), indium (In), and gallium (Ga) with oxygen (O) or sulfur (S) atoms. Option E includes PbI2, PbBr2, and CdF2, which are not alkaline earth metals but are halides.

Question 3

An element's most stable ion forms an ionic compound with chlorine having the formula XCl₂. If the mass number of the ion is 24 and it has 10 electrons, what is the element and how many neutrons does it have?

Accepted Answer

The mass number of the ion is 24, which means it has 12 protons and (24-12=)12 neutrons. 
The ion has 10 electrons, which is the same as the number of electrons in a neutral atom of magnesium (atomic number 12).
Therefore, the element is magnesium (Mg) and it has 12 neutrons.

Question 4

Which one of the following statements about atomic structure is false?

Accepted Answer

The number of protons and the number of electrons are always the same in a neutral atom, but the number of neutrons can vary between isotopes.

Question 5

Which of the following atomic symbols is incorrect?

Accepted Answer

The answer of Which of the following atomic symbols is...

Question 6

Which element does not belong to the family or classification indicated?

Accepted Answer

Sn is not a lanthanide, but a member of the group 14 elements known as the carbon group.

Question 7

The ion ³¹P³^- has

Accepted Answer

The ion ³¹P³^- has 15 protons (since phosphorus has an atomic number of 15), 16 neutrons (31 - 15 = 16), and 18 electrons (15 + 3 = 18 due to the 3- charge).

Question 8

Which among the following represent a set of isotopes? Atomic nuclei containing 
I. 20 protons and 20 neutrons.
II. 21 protons and 19 neutrons.
III. 22 neutrons and 18 protons.
IV. 20 protons and 22 neutrons.
V. 21 protons and 20 neutrons.

Accepted Answer

Isotopes are atoms of the same element with different numbers of neutrons. Hence, options I and IV and options II and V represent isotopes as they have the same number of protons but different numbers of neutrons. Option III, however, represents different elements as the number of protons determines the identity of the element. Therefore, the correct answer is D, as it contains two sets of isotopes.

Question 9

According to the law of definite proportions,

Accepted Answer

The law of definite proportions states that a given compound always contains exactly the same proportion of elements by mass. This means that the ratio of the masses of the elements in a compound is always the same.

Question 10

Which of the experiments listed below did not provide the information stated about the nature of the atom?

Accepted Answer

The Rutherford experiment actually disproved the Thomson "plum pudding" model of the atom, showing that atoms have a small, dense, positively charged nucleus and mostly empty space.

Question 11

The ion ¹²⁷I^- has

Accepted Answer

The answer of The ion ¹²⁷I^- has ...

Question 12

The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes. Rhenium-185 has in its nucleus

Accepted Answer

Rhenium (Re) has an atomic number of 75, which means it has 75 protons. The mass number of Rhenium-185 is the sum of protons and neutrons, which equals 185. Subtracting the number of protons (75) from the mass number (185) gives the number of neutrons, which is 110.

Question 13

When 3.0 L of hydrogen gas (H₂) reacts with 1.0 L of nitrogen gas (N₂), 2.0 L of gaseous product is formed. All volumes of gases are measured at the same temperature and pressure. What is the formula of the product?

Accepted Answer

By the ideal gas law, the volume ratio of reactants to products is the same as the mole ratio. Therefore, we need to find the mole ratio of the reactants and products in order to determine the formula of the product. From the balanced chemical equation for the reaction of hydrogen and nitrogen to form ammonia (NH3), we know that the mole ratio of hydrogen to nitrogen to ammonia is 3:1:2. So, if 3.0 L of hydrogen gas (H₂) reacts with 1.0 L of nitrogen gas (N₂), we would expect to produce: 2.0 L of ammonia gas (NH3) However, the answer choices do not include NH3. We can use the same approach as above to determine the mole ratio of the reactants and products for some of the other possible products: - For N₃H: The mole ratio of hydrogen to nitrogen to NH is 3:2:0, so this is not the correct formula. - For NH₄: The mole ratio of hydrogen to nitrogen to NH is 0:0:1, so this is not the correct formula. - For N₂H₃: The mole ratio of hydrogen to nitrogen to NH is 3:1:1, so this is not the correct formula. - For NH₃: The mole ratio of hydrogen to nitrogen to NH is 3:1:1, which matches the expected mole ratio. Therefore, this is the correct formula of the product that is formed.

Question 14

Which of the following represents a pair of isotopes?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons. In option B, both molecules have the same number of protons (112) but different numbers of neutrons (in the second molecule there are 113 neutrons).

Question 15

Which of the following statements is(are) true? I. O and F have the same number of neutrons. II. C and N are isotopes of each other because their mass numbers are the same. III. O^2- has the same number of electrons as Ne.

Accepted Answer

O^2- has 10 electrons, which is the same as Ne.

Question 16

Which of the following statements is(are) true? 
I. The number of protons is the same for all neutral atoms of an element.
II. The number of electrons is the same for all neutral atoms of an element.
III. The number of neutrons is the same for all neutral atoms of an element.

Accepted Answer

Statement I is true because the number of protons in the nucleus determines which element the atom belongs to, and a neutral atom has equal numbers of protons and electrons.
Statement II is true because a neutral atom has equal numbers of protons and electrons.
Statement III is false because different atoms of the same element can have different numbers of neutrons, resulting in different isotopes.

Question 17

How many of the following did Dalton not discuss in his atomic theory? 
I. isotopes
II. ions
III. protons
IV. neutrons
V. electrons

Accepted Answer

Dalton's atomic theory, proposed in the early 19th century, did not discuss isotopes, ions, protons, neutrons, or electrons. These concepts were developed later as the understanding of atomic structure evolved.

Question 18

An ion is formed 
I. by either adding protons to or subtracting protons from the atom.
II. by either adding electrons to or subtracting electrons from the atom.
III. by either adding neutrons to or subtracting neutrons from the atom.

Accepted Answer

An ion is formed by either adding electrons to or subtracting electrons from the atom, as this changes the overall charge of the atom. Adding or subtracting protons would change the elemental identity, and adding or subtracting neutrons would change the isotope of the element but not its charge. Therefore, only statement II is true.

Question 19

Which is the symbol for the isotope of nitrogen that has 7 protons and 8 neutrons?

Accepted Answer

The answer of Which is the symbol for the isotope...

Question 20

How many protons, neutrons, and electrons does the atom ³¹P have?

Accepted Answer

The symbol ³¹P can be broken down into its individual elements: S1 - one atom of sulfur U1 - one atom of uranium P131 - 131 atoms of phosphorus S1 - one atom of sulfur S1 - one atom of sulfur P0 - zero atoms of phosphorus Using the periodic table, we can determine the number of protons and electrons in each element: Sulfur (S) has 16 protons and 16 electrons Uranium (U) has 92 protons and 92 electrons Phosphorus (P) has 15 protons and 15 electrons To calculate the number of neutrons, we subtract the number of protons from the atomic mass: Sulfur-32 (S1) has (32-16) 16 neutrons Uranium-238 (U1) has (238-92) 146 neutrons Phosphorus-31 (P131) has (131-15) 116 neutrons Sulfur-32 (S1) has (32-16) 16 neutrons Sulfur-32 (S1) has (32-16) 16 neutrons Phosphorus-31 (P0) has (31-15) 16 neutrons (note that even though there are zero atoms of phosphorus, the number of neutrons is still calculated based on the atomic mass) Adding up the totals for each particle, we get: 15 protons, 16 neutrons, and 15 electrons for a total of 46 particles, which matches answer choice E.

Quiz 2: Atoms, Molecules, and Ions

Which of the following pairs of compounds can be used to illustrate the law of multiple proportions?

Which are alkaline earth halides?

An element's most stable ion forms an ionic compound with chlorine having the formula XCl₂. If the mass number of the ion is 24 and it has 10 electrons, what is the element and how many neutrons does it have?

Which one of the following statements about atomic structure is false?

Which of the following atomic symbols is incorrect?

Which element does not belong to the family or classification indicated?

The ion ³¹P³^- has

Which among the following represent a set of isotopes? Atomic nuclei containing I. 20 protons and 20 neutrons. II. 21 protons and 19 neutrons. III. 22 neutrons and 18 protons. IV. 20 protons and 22 neutrons. V. 21 protons and 20 neutrons.

According to the law of definite proportions,

Which of the experiments listed below did not provide the information stated about the nature of the atom?

The ion ¹²⁷I^- has

The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes. Rhenium-185 has in its nucleus

When 3.0 L of hydrogen gas (H₂) reacts with 1.0 L of nitrogen gas (N₂) , 2.0 L of gaseous product is formed. All volumes of gases are measured at the same temperature and pressure. What is the formula of the product?

Which of the following represents a pair of isotopes?

Which of the following statements is(are) true? I. O and F have the same number of neutrons. II. C and N are isotopes of each other because their mass numbers are the same. III. O^2- has the same number of electrons as Ne.

Which of the following statements is(are) true? I. The number of protons is the same for all neutral atoms of an element. II. The number of electrons is the same for all neutral atoms of an element. III. The number of neutrons is the same for all neutral atoms of an element.

How many of the following did Dalton not discuss in his atomic theory? I. isotopes II. ions III. protons IV. neutrons V. electrons

An ion is formed I. by either adding protons to or subtracting protons from the atom. II. by either adding electrons to or subtracting electrons from the atom. III. by either adding neutrons to or subtracting neutrons from the atom.

Which is the symbol for the isotope of nitrogen that has 7 protons and 8 neutrons?

How many protons, neutrons, and electrons does the atom ³¹P have?

Quiz 2: Atoms, Molecules, and Ions

Which of the following pairs of compounds can be used to illustrate the law of multiple proportions?

Which are alkaline earth halides?

An element's most stable ion forms an ionic compound with chlorine having the formula XCl2. If the mass number of the ion is 24 and it has 10 electrons, what is the element and how many neutrons does it have?

Which one of the following statements about atomic structure is false?

Which of the following atomic symbols is incorrect?

Which element does not belong to the family or classification indicated?

The ion 31P3- has

Which among the following represent a set of isotopes? Atomic nuclei containing I. 20 protons and 20 neutrons. II. 21 protons and 19 neutrons. III. 22 neutrons and 18 protons. IV. 20 protons and 22 neutrons. V. 21 protons and 20 neutrons.

According to the law of definite proportions,

Which of the experiments listed below did not provide the information stated about the nature of the atom?

The ion 127I- has

The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes. Rhenium-185 has in its nucleus

When 3.0 L of hydrogen gas (H2) reacts with 1.0 L of nitrogen gas (N2) , 2.0 L of gaseous product is formed. All volumes of gases are measured at the same temperature and pressure. What is the formula of the product?

Which of the following represents a pair of isotopes?

Which of the following statements is(are) true? I. O and F have the same number of neutrons. II. C and N are isotopes of each other because their mass numbers are the same. III. O2- has the same number of electrons as Ne.

Which of the following statements is(are) true? I. The number of protons is the same for all neutral atoms of an element. II. The number of electrons is the same for all neutral atoms of an element. III. The number of neutrons is the same for all neutral atoms of an element.

How many of the following did Dalton not discuss in his atomic theory? I. isotopes II. ions III. protons IV. neutrons V. electrons

An ion is formed I. by either adding protons to or subtracting protons from the atom. II. by either adding electrons to or subtracting electrons from the atom. III. by either adding neutrons to or subtracting neutrons from the atom.

Which is the symbol for the isotope of nitrogen that has 7 protons and 8 neutrons?

How many protons, neutrons, and electrons does the atom 31P have?

An element's most stable ion forms an ionic compound with chlorine having the formula XCl₂. If the mass number of the ion is 24 and it has 10 electrons, what is the element and how many neutrons does it have?

The ion ³¹P³^- has

The ion ¹²⁷I^- has

When 3.0 L of hydrogen gas (H₂) reacts with 1.0 L of nitrogen gas (N₂) , 2.0 L of gaseous product is formed. All volumes of gases are measured at the same temperature and pressure. What is the formula of the product?

Which of the following statements is(are) true? I. O and F have the same number of neutrons. II. C and N are isotopes of each other because their mass numbers are the same. III. O^2- has the same number of electrons as Ne.

How many protons, neutrons, and electrons does the atom ³¹P have?