* not completed

. Identify the correct statement related to the Lewis structures and octet rule:

After a single bond is formed between the central atom and each terminal atom, any unused electrons are first added as lone electron pairs on the central atom. correct incorrect

Generally, the atom of highest electronegativity is a central atom in the Lewis structure. correct incorrect

The number of electrons that have to be included in the Lewis structure is obtained by adding all the valence electrons from all atoms forming the structure. correct incorrect

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. Which of the following statements correctly describes a resonance hybrid:

Resonance hybrid is a blended structure obtained from two or more Lewis structures. correct incorrect

If more than one acceptable Lewis structure can be drawn for a molecule or ion, then the structure with no formal charges is called resonance hybrid. correct incorrect

The structure in which the central atom does not have an extended octet is called a resonance hybrid. correct incorrect

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. What is the oxidation number of Na and O in Na₂O₂?

+1 for sodium and –1 for oxygen correct incorrect

+1 for sodium and –2 for oxygen correct incorrect

+1 for sodium and –1/2 for oxygen correct incorrect

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. Examine the Lewis structure of SF₆ in your textbook (structure 16 on p. 41). This structure is an example of:

an expanded octet on the central atom (sulfur) correct incorrect

incorrectly written Lewis structure correct incorrect

incomplete octet correct incorrect

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. "Both XeF₄ and CF₄ possess tetrahedral molecular geometries." Choose the correct response to this statement.

Only tetrafluoromethane is tetrahedral. correct incorrect

Both are molecules of the type AX₄ (A is the central atom, X is the terminal atom), so the statement is correct. correct incorrect

No, the molecular geometries of both molecules are square planar. correct incorrect

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. The ground-state configuration of the nitrogen atom is [He]2s²2p³. Use the valence-bond theory to predict the type of bond between two nitrogen atoms forming a nitrogen molecule.

a single, σ-bond correct incorrect

a triple bond consisting of three σ-bonds correct incorrect

a triple bond consisting of one σ- and two π-bonds correct incorrect

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. Using the framework of the molecular orbital theory, recall the meaning of bond order and select the correct statement:

For a given pair of atoms, as the bond order increases, so does the bond enthalpy, but the bond length decreases. correct incorrect

For a given pair of atoms, as the bond order increases, so does the bond length, but the bond enthalpy decreases. correct incorrect

For a given pair of atoms, as the bond order increases, so do the bond length, and the bond enthalpy. correct incorrect

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. Using the electronegativity data from Chapter 1, Table 1.7 and Ketelaar triangle (Figure 2.28) determine the likely bond type in BeO:

ionic correct incorrect

covalent correct incorrect

metallic. correct incorrect

* not completed

. How does catalysis work?

It speeds up a reaction by lowering the Gibbs energy of activation. correct incorrect

It speeds up a reaction by lowering the Gibbs energy of the chemical reaction. correct incorrect

It speeds up a reaction by stabilizing the reaction-activated complex. correct incorrect

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. The difference between homo- and heterogeneous catalysts is that:

Homogeneous catalysts are present in the same phase with the products; heterogeneous ones are not. correct incorrect

Homogeneous catalysis are well mixed (homogenized), while heterogeneous catalysts are not. correct incorrect

Homogeneous catalysts are present in the same phase with the reagents; heterogeneous ones are not. correct incorrect