Question 1

There are three isotopes of oxygen ¹⁶O,¹⁷O and ¹⁸O.Indicate the number of different types of isotopically substituted diatomic oxygen.

Accepted Answer

Isotopically substituted diatomic oxygen molecules can be formed by combining the three isotopes of oxygen in pairs. The combinations are: ^16O^16O, ^16O^17O, ^16O^18O, ^17O^17O, ^17O^18O, and ^18O^18O, making a total of 6 different types.

Question 2

What is the molecular structure of phosphorous acid?

Accepted Answer

The answer of What is the molecular structure of phosphorous...

Question 3

What are the molecular structures of orthophosphoric acid and pyrophosphoric acid?

Accepted Answer

The answer of What are the molecular structures of orthophosphoric...

Question 4

There are three different isotopes of hydrogen ¹H,²H,³H and three different isotopes of oxygen ¹⁶O,¹⁷O,¹⁸O.Indicate the number of different types of isotopically substituted water,H₂O,that could be formed.

Accepted Answer

With three isotopes of hydrogen and three isotopes of oxygen, the number of different isotopically substituted water molecules that can be formed is the product of the number of isotopes of each element, which is 3 hydrogen isotopes * 3 oxygen isotopes = 9. However, since water has two hydrogen atoms, we need to consider combinations of hydrogen isotopes as well. There are 3 choices for the first hydrogen atom and 3 choices for the second, giving 3 * 3 = 9 combinations of hydrogen alone. When combined with the 3 choices of oxygen isotopes, the total number of different isotopically substituted water molecules is 9 * 3 = 27. However, since the question specifies the formula as H2O, implying the consideration of each hydrogen isotope in combination with an oxygen isotope without distinguishing between the positions of the two hydrogen atoms (which would matter for molecules where the position could lead to different compounds, but not in the case of water due to its symmetrical nature), the correct interpretation should indeed reflect the basic combinations without overcounting for indistinguishable arrangements, leading to the initial calculation of 9 combinations of hydrogen (accounting for identical combinations as a single unique type due to the indistinguishable nature of the hydrogen atoms in water) and 3 of oxygen, which was an error in my explanation. The correct calculation, considering each hydrogen isotope can pair with each oxygen isotope and not overcounting identical hydrogen combinations, should indeed be 3 hydrogen isotopes * 3 oxygen isotopes = 9 unique types of water, which contradicts my initial conclusion. Therefore, the correct answer, based on the straightforward combination of available isotopes without overcomplicating the calculation, should be:AEach hydrogen isotope can combine with each oxygen isotope, resulting in 3*3 = 9 unique isotopically substituted water molecules.

Question 5

Which elements of group 6A are oxidizing agents and which are reducing agents?

Accepted Answer

Oxygen (O) and sulfur (S) are strong oxidizing agents because they readily gain electrons. Selenium (Se) and tellurium (Te) can act as reducing agents, especially in comparison to oxygen and sulfur, because they are more likely to donate electrons.

Question 6

Commercially oxygen is usually obtained by

Accepted Answer

Commercially, oxygen is usually obtained by fractional distillation of air. Air is separated into its component gases using cryogenic distillation, with oxygen being one of the gases collected. This method is more efficient and cost-effective than other methods such as the electrolytic decomposition of water or the decomposition of mercury(II) oxide.

Question 7

What are the signs are expected for the entropy change ΔS and free energy change ΔG for the reaction below? N₂H₄(l)+ N₂O₄(l)→ 3 N₂(g)+ 4 H₂O(g)ΔH = -1049 kJ

Accepted Answer

The reaction involves the conversion of liquids to gases, which increases the disorder in the system, indicating a positive change in entropy (ΔS > 0). Given that the reaction is exothermic (ΔH < 0) and increases disorder, it is likely to be spontaneous at standard conditions, suggesting a negative change in free energy (ΔG < 0).

Question 8

What is not an appropriate method of making phosphoric acid?

Accepted Answer

Option D shows a reaction that is not feasible for the production of phosphoric acid. The reaction shown in option D only produces water and does not involve any phosphorus compound, therefore not suitable for making phosphoric acid. Options A, B, and C involve phosphorus compounds and are feasible methods for producing phosphoric acid.

Question 9

A 0.010 M solution of which of the following would have the lowest pH?

Accepted Answer

NH₂OH has the lowest K_b value, indicating it is the weakest base among the options, resulting in the lowest pH for its solution.

Question 10

Which is not true about elemental oxygen?

Accepted Answer

Oxygen is an oxidizing agent, not a reducing agent.

Question 11

What is the structure of white phosphorus?

Accepted Answer

White phosphorus consists of discrete P4 tetrahedral molecules.

Question 12

What is an appropriate method for the synthesis of phosphorus?

Accepted Answer

The correct method for synthesizing phosphorus involves the reduction of phosphate ores with carbon and silicon dioxide at high temperatures, which is represented by the chemical equation in option A.

Question 13

What is responsible for the brownish colored gas when copper dissolves in nitric acid?

Accepted Answer

The brownish colored gas produced when copper dissolves in nitric acid is nitrogen dioxide (NO2), which is represented by the reaction in choice A.

Question 14

Using the three different isotopes of oxygen ¹⁶O,¹⁷O,¹⁸O and the major isotope of hydrogen,¹H.Determine the number of different types of isotopically substituted hydrogen peroxide,H₂O₂,that could be formed.

Accepted Answer

Isotopically substituted hydrogen peroxide molecules can be formed by replacing one or both hydrogen atoms with one of the three oxygen isotopes (16O, 17O, or 18O). Since there is only one major isotope of hydrogen (1H), there are three possible isotopic substitutions for each hydrogen atom in H2O2. Thus, there are 3 × 3 = 9 possible isotopically substituted hydrogen peroxide molecules in total. However, since the two hydrogen atoms in H2O2 are identical, some of these molecules will be chemically identical to each other. Specifically, exchanging two hydrogen atoms with the same isotope will result in the same molecule, regardless of which two hydrogens are exchanged. This means that there are actually only six chemically distinct isotopically substituted hydrogen peroxide molecules.

Question 15

What statement is not characteristic about group 6A elements?

Accepted Answer

Group 6A elements have a favored oxidation state of -2. However, the statement in choice D suggests that Te and Po have a favored oxidation state of +2, which is not characteristic of group 6A elements.

Question 16

What is the most acidic oxide of phosphorus?

Accepted Answer

P4O10 is the most acidic oxide of phosphorus because it reacts with water to form phosphoric acid (H3PO4), which is a strong acid.

Question 17

Which one of the following binary oxides is the most basic?

Accepted Answer

In2O3 (Indium(III) oxide) is the most basic among the given options because indium is located further down the group in the periodic table, which generally increases the basicity of the oxides.

Question 18

What statement about nitric acid is not true?

Accepted Answer

The statement that nitric acid's anhydride is N₂O₃ is not true. The correct anhydride for nitric acid is N2O5.

Question 19

What is not a characteristic of white phosphorus?

Accepted Answer

White phosphorus does not convert to red phosphorus at temperatures less than 0°C. The conversion to red phosphorus is a process that requires higher temperatures and/or the presence of light, not merely low temperatures.

Question 20

A 0.010 M solution of which of the following would have the highest pH?

Accepted Answer

The compound with the highest Kb value will have the highest pH, as it is the strongest base. (CH3)2NH has the highest Kb value of 5.4 × 10^-4 among the given options.

Quiz 22: The Main-Group Elements

There are three isotopes of oxygen ¹⁶O,¹⁷O and ¹⁸O.Indicate the number of different types of isotopically substituted diatomic oxygen.

What is the molecular structure of phosphorous acid?

What are the molecular structures of orthophosphoric acid and pyrophosphoric acid?

There are three different isotopes of hydrogen ¹H,²H,³H and three different isotopes of oxygen ¹⁶O,¹⁷O,¹⁸O.Indicate the number of different types of isotopically substituted water,H₂O,that could be formed.

Which elements of group 6A are oxidizing agents and which are reducing agents?

Commercially oxygen is usually obtained by

What are the signs are expected for the entropy change ΔS and free energy change ΔG for the reaction below? N₂H₄(l) + N₂O₄(l) → 3 N₂(g) + 4 H₂O(g) ΔH = -1049 kJ

What is not an appropriate method of making phosphoric acid?

A 0.010 M solution of which of the following would have the lowest pH?

Which is not true about elemental oxygen?

What is the structure of white phosphorus?

What is an appropriate method for the synthesis of phosphorus?

What is responsible for the brownish colored gas when copper dissolves in nitric acid?

Using the three different isotopes of oxygen ¹⁶O,¹⁷O,¹⁸O and the major isotope of hydrogen,¹H.Determine the number of different types of isotopically substituted hydrogen peroxide,H₂O₂,that could be formed.

What statement is not characteristic about group 6A elements?

What is the most acidic oxide of phosphorus?

Which one of the following binary oxides is the most basic?

What statement about nitric acid is not true?

What is not a characteristic of white phosphorus?

A 0.010 M solution of which of the following would have the highest pH?

Quiz 22: The Main-Group Elements

There are three isotopes of oxygen 16O,17O and 18O.Indicate the number of different types of isotopically substituted diatomic oxygen.

What is the molecular structure of phosphorous acid?

What are the molecular structures of orthophosphoric acid and pyrophosphoric acid?

There are three different isotopes of hydrogen 1H,2H,3H and three different isotopes of oxygen 16O,17O,18O.Indicate the number of different types of isotopically substituted water,H2O,that could be formed.

Which elements of group 6A are oxidizing agents and which are reducing agents?

Commercially oxygen is usually obtained by

What are the signs are expected for the entropy change ΔS and free energy change ΔG for the reaction below? N2H4(l) + N2O4(l) → 3 N2(g) + 4 H2O(g) ΔH = -1049 kJ

What is not an appropriate method of making phosphoric acid?

A 0.010 M solution of which of the following would have the lowest pH?

Which is not true about elemental oxygen?

What is the structure of white phosphorus?

What is an appropriate method for the synthesis of phosphorus?

What is responsible for the brownish colored gas when copper dissolves in nitric acid?

Using the three different isotopes of oxygen 16O,17O,18O and the major isotope of hydrogen,1H.Determine the number of different types of isotopically substituted hydrogen peroxide,H2O2,that could be formed.

What statement is not characteristic about group 6A elements?

What is the most acidic oxide of phosphorus?

Which one of the following binary oxides is the most basic?

What statement about nitric acid is not true?

What is not a characteristic of white phosphorus?

A 0.010 M solution of which of the following would have the highest pH?

There are three isotopes of oxygen ¹⁶O,¹⁷O and ¹⁸O.Indicate the number of different types of isotopically substituted diatomic oxygen.

There are three different isotopes of hydrogen ¹H,²H,³H and three different isotopes of oxygen ¹⁶O,¹⁷O,¹⁸O.Indicate the number of different types of isotopically substituted water,H₂O,that could be formed.

What are the signs are expected for the entropy change ΔS and free energy change ΔG for the reaction below? N₂H₄(l) + N₂O₄(l) → 3 N₂(g) + 4 H₂O(g) ΔH = -1049 kJ

Using the three different isotopes of oxygen ¹⁶O,¹⁷O,¹⁸O and the major isotope of hydrogen,¹H.Determine the number of different types of isotopically substituted hydrogen peroxide,H₂O₂,that could be formed.