Unit 2 Test AP Chem (test questions)

A lewis diagram for the molecule is shown. In the actual molecule the bond angles are closest to the image.

120 degrees.

Copper atoms and zinc atoms have the same atomic radius, 135 picometers. Based on this information, which of the following diagrams best represents an alloy containing only copper and zinc atoms?

B.

Which of the following Lewis electron-dot diagrams represents the molecule contains the smallest bond angle?

B.

Which has a central atom with less than an octet of electrons?

BH3

In the reaction represented, which of the following sets correctly identifies the hybridization of the atoms before and after the reaction occurs.

Before, sp^2 After, sp^3

which molecule has only one double bond?

C2H4

Which of the following molecules contains only single bonds?

C2H6

On the basis of the information, which of the following arranges the binary compounds in order of increasing bond polarity?

CH4< SiCl4< SF4

To make Au stronger and harder, it is often alloyed with other metals, such as Cu and Ag. Consider two alloys, one of Au and Cu and one of Au and Ag, each with the same mole fraction of Au. If the Au/Cu alloy is harder than the Au/Ag alloy, then which of the following is the best explanation based on the information in the table above?

Cu atoms are smaller than Ag atoms, thus they interfere more with the displacement of atoms in the alloy.

Which of the following graphs correctly shows the relationship between potential energy and inter nuclear separation for 2 H atoms?

Graph D.

Which has 2 lone pairs of electrons?

H2O

The electron-dot structure for which of the following molecules would have 2 unshared pairs of electrons on the central atoms?

H2S

According to the VSEPR model, the progressive decrease in the bond angles in the series of molecules CH4, NH3, and H2O is best accounted for by the

Increasing number of unshared pairs of electrons.

Two pure elements react to form a compound. One element is an alkali metal, X, and the other element is a halogen, Z. Which of the following is the most valid scientific claim that can be made about the compound?

It contains ionic bonds.

The lattice energy of a salt is related to the energy required to separate the ions. For which of the following pairs of ions is the energy that is required to separate the ions largest? (Assume that the distance between the ions in each pair is equal to the sum of the ionic radii)

Mg^2+ (g) and O^2- (g).

Shortest bond length?

N2

Which molecule has a pyramid geometry?

NH3 (g)

Which has a bond order of 2?

O2

Resonance is most commonly used to describe the bonding in molecules of which of the following?

O3

Which of the following molecules has a bent geometry that is commonly represented as a resonance hybrid of 2 or more electron-dot structures?

O3

Which molecule has trigonometrical pyramid geometry?

PH3

Which is a polar molecule?

SO2

The elements C and Se have the same electronegativity value, 2.55. Which of the following claims about the compound that forms from C and Se is most likely to be true?

The C-Se bond is nonpolar covalent

Which of the following can be inferred from the diagram above that shows the dependence of potential energy on the internuclear distance between two atoms?

The atoms form a bond with a bond length of 75 pm.

The potential energy of a system of 2 atoms as a function of their inter nuclear distance is shown in the diagram. Which of the following is true regarding the forces between the atoms when their inter nuclear distance is x?

The attractive and repulsive forces are balanced, so the atoms will maintain an average internuclear distance.

The table shows the melting points of MgO(s) and NaF(s). Which of the following best helps explain why the melting points of MgO(s) is so much higher than that of NaF(s)?

The charges of Mg^2+ and O^2- are greater than that of Na+ and F- ions.

The physical energy as a function of inter nuclear distance for 3 diatomic molecules, X2, Y2 and Z2, is shown in the graph above. Based on the data in the graph, which of the following correctly identifies the diatomic molecules, X2, Y2, and Z2?

X2= H2 Y2= N2 Z2= O2

When Reaction 3 occurs, does the hybridization of the carbon atoms change?

Yes, it changes from sp to sp^2.

The hybridization of the carbon atoms in the molecule represented can be described as... (look at the image).

sp^3