Exam Midterm Prep
Which of the following best explains why more energy is required for the pocess ocurring at 110 K than for the process occuring at 90 K?
A) Intermolecular attractions are completely overcome during vaporization
Which of the following molecules has the shortest bond length?
A) N2
Which of the following diagrams best depicts an alloy of Ni and B?
A
Has the largest atomic radius
A) Cs
Consider atoms of the following elements. Assume that the atoms are in the ground state
A) S
In his atomic theory, Dalton proposed that all atoms of a given element are identical. Which of the following observations provides the best evidence that the proposal is incorrect?
A) The mass spectrum of Cu has a peak at 63 amu and another peak at 65 amu
A sample containing atoms of C and F was analyzed using x-ray photoelectron spectroscopy. The portion of the spectrum showing the 1s peaks for atoms for atoms of the two elements is shown above. Which of the following correctly identifies the 1s peak for the F atoms and provides an appropriate explanation?
B) Peak X, because F has greater nuclear charge than C has.
Is a polar molecule
B) SO2
Which of the following can be inferred from the diagram above that shows the dependence of potential energy on the internuclear between two atoms?
B) The atoms form a bond with a bond length of 75 pm.
Steel is an alloy...
B) see exam prep
The elements I and Te have similar average atomic masses. A sample that was believed to be a mixture of I and Te was run through mass spectrometer, resulting in the data above. All of the following statements are true. Which one would be the best basis for concluding that the sample was pure Te?
C) I consists of only one naturally occurring isotope with 74 neutrons, whereas Te has more than one isotope
Of the following single bonds, which is the LEAST polar?
C) O--F
Which of the following ions has the same number of electrons as Br^-?
C) Sr^2+
For element X represented above, which of the following is the most likely explanation for the large difference between the second and third ionization energies?
C) The electron removed during the third ionization is, on average, much closer to the nucleus than the first two electrons removed were.
Solid ethyl alcohol, C2H5OH
C) a molecular solid with hydrogen bonding
In solid methane, the forces between neighboring Ch4 molecules are best characterized as
E) London (dispersion) forces
In the diagram above, which of the labeled arrows indentifies hydrogen bonding in water
D) D
Which of the following diagrams best illustrates how a displacement in an ionic crystal result in cleavage and brittleness?
A
The London (dispersion) forces are weakest for which of the following gases under the same conditions of temperature and pressure?
A) H2
The electron-dot structure (Lewis structure) for which of the following molecules would have two unshared pairs of electrons on the central atom?
A) H2S
Based on the data in the tables above, which of the following statements provides the best prediction for the boiling point of NaCl?
A) NaCl will have a lower boiling point than NaF because the coulombic attractions are weaker in NaCl than in NaF
The first five ionization energies of a second period element are listed in the table above. Which of the following correctly identifies the element and best explains the data in the table?
B) B, because it has three valence electrons
Atoms of Mg combine with atoms of F to form a compound. Atoms of which of the following elements combine with atoms of F in the same ratio?
B) Ba
The structure of one form of boron nitride is respresneted above. This form of boron nitride is one of the hardest substances known. Which of the following is best helps explain why boron nitride is so hard?
B) Boron nitride is a network solid of atoms connected by covalent bond with bond angles
In which of the following compounds is the mass ratio of chromium to oxygen closest to 1.62 to 1.00?
B) CrO^2
The ionic compounds NaCl and MgS are represented by the diagrams above. Which statement correctly identifies diagram 1 and identifies the compound with the lower melting point, explaining why?
B) Diagram 1 represents NaCl; it has a lower melting point than MgS because the coulombic attractions between its singly charged Na^+ ion and the Cl^- ions are weaker than those between the ions in MgS
Which of the following best helps to account for the fact that the F^- ion is smaller than the O^2- ion?
B) F^- has a larger nuclear charge than O^2- has
The molecule with the largest dipole movement
B) H2O
The melting point of MgO is higher than that of NaF. Explanations for this observation include which of the following? I. Mg^2+ is more positively charged than Na^+ II. O^2- is more negatively charged than F^- III. The O^2- ion is smaller than the F^- ion
B) I and II only
According to the information in the table above, a 1.00 g sample of which of the following contains the greatest mass of oxygen?
B) MgO
A sample of a pure compound is analyzed and found to contain approximately 30 percent N and 70 percent O by mass. The formula for the compound could be
B) NO^2
The effective nuclear charge experienced by the outermost electron of Na is different than the effective nuclear charge experienced by the outermost electron of Ne. This difference best account for which of the following?
B) Na has a lower first ionization energy than Ne
A Lewis diagram for the molecule C2H4 is shown above. In the actual C2h4 molcule, the H-C-H bond angels are closest to
C) 120
If the pressure of each gas is increased at constant temperature until condensation occurs, which gas will condense at the lowest pressure?
C) Butane
Based on the data in the table above, which of the following liquid substances has the weakest intermolecular forces?
C) CH3OH(l)
Which of the following substances has bonds with the greatest ionic character?
C) CaCl2
The four species above have the same electron configuration, 1s^2 2s^2 2p^6 3s^2 3p^6. Which of the following statement correctly identifies the species with the largest radius and provides an explanation based on Coulomb's
Cl^-, because its nuclear charge exerts the least attractive force on the electrons in the 3p sublevel
Which of the following best helps to explain why hexane has a higher boiling point than methanol has?
D) Hexane molecules have electron clouds that are larger than those of methanol molecules.
A student has a 1g sample of each of the following compounds: NaCl, KBr, and KCl. Which of the following lists the samples in order of increasing number of moles in the sample?
D) KBr < KCl < NaCl
The photoelectron spectra above show the energy required to remove a 1s electron from of nitrogen atom and from an oxygen atom. Which of the following statements best accounts for the peak in the upper spectrum being right of the peak in the lower spectrum?
D) Nitrogen atoms have a smaller nuclear charge than oxygen atoms
Based on the information above and periodic trends, which of the following is best hypothesis regarding the oxide(s) formed by Rb?
D) Rb will form Rb2O2 and RbO2
The mass spectrum of element X is prepared in the diagram above. Based on the spectrum, which of the following can be concluded about element X?
D) The atomic mass of X is between 90 and 92
The table above shows the melting points of MGO(s) and NaF(s). Which of the following best helps explain why the melting point of MgO(s) is much higher than that of NaF(s)?
D) The charges of Mg^2+ and O^2- ions are greater than those of Na+ and F-
The photoelectron spectrum for the element nitrogen is represented above. Which of the following best explains how the spectrum is consistent with the electron shell model of the atom?
D) The electrons in the 2p sublevel have the smallest binding energy.
Of the following compounds, which is the most ionic?
E) CaCl2
