ap chem final review

The diagram above represents the absorption spectrum for a pure molecular substance. Which of the following correctly indicates the type of transition observed for the substance in each of the regions of the absorption spectrum?

(D)Electronic transitionMolecular vibrationMolecular rotation

The question refers to the following species. (A) H2O (B) NH3 (C) BH3 (D) CH4 (E) SiH4 14. Has two lone pairs of electrons

A) H2O

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 .

A balloon filled with 0.25 mol of He(g) at 273 K and 1 atm is allowed to rise through the atmosphere. Which of the following explains what happens to the volume of the balloon as it rises from ground level to an altitude where the air temperature is 220 K and the air pressure is 0.1 atm?

A) The volume will increase because the decrease in air pressure will have a greater effect than the decrease in temperature.

Which of the following statements, if true, would support the claim that the NO3− ion, represented above, has three resonance structures?

A)The ion is not a polar species.

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

D) A molecule of the compound will have a partial negative charge on the carbon atom.

If reacts with chlorine to form , which of the following elements reacts with to form an ionic compound in a one-to-one ratio, and why?

D) Br, because it has the same number of valence electrons as Cl.

Which of the molecules represented below contains carbon with sp2 hybridization?

D) C2H2Cl2

The photoelectron spectra above show the energy required to remove a 1s electron from a nitrogen atom and from an oxygen atom. Which of the following statements best accounts for the peak in the upper spectrum being to the right of the peak in the lower spectrum?

D) Nitrogen atoms have a smaller nuclear charge than oxygen atoms

Based on the information in the table above, which of the compounds has the highest boiling point, and why?

D) Propanoic acid, because it can form intermolecular hydrogen bonds

Which of the following best helps to explain why CCl4 is a liquid whereas CI4 is a solid when both are at 25°C?

D) The London dispersion forces are stronger in CI4 than in CCl4 because CI4 has a more polarizable electron cloud than CCl4

The energy required to dissociate an ionic solid into gaseous ions (lattice energy) for the compounds andis shown in the table above. On the basis of Coulomb's law, which of the following best helps to explain the large difference between the lattice energies of and ?

D) The charge of the Mg cation is larger than that of the Na cation.

The diagram above is a molecular model of a gaseous diatomic element that is just above its boiling point. Intermolecular forces between the gas molecules will cause them to condense into the liquid phase if the temperature is lowered. Which of the following best describes how the model is limited in its depiction of the phenomenon?

D)It does not show how the temporary fluctuating dipoles of the molecular electron clouds result in a net force of attraction between the molecules.

A student prepared five solutions of CuSO4 with different concentrations, and then filled five cuvettes, each containing one of the solutions. The cuvettes were placed in a spectrophotometer set to the appropriate wavelength for maximum absorbance. The absorbance of each solution was measured and recorded. The student plotted absorbance versus concentration, as shown in the figure above. Which of the following is the most likely explanation for the variance of the data point for the 0.600 M CuSO4 solution?

D)The cuvette used for the 0.600 M solution had not been wiped clean before being put in the spectrophotometer.

A student obtains a mixture of the liquids hexane and octane, which are miscible in all proportions. Which of the following techniques would be best for separating the two components of the mixture, and why?

Distillation, because the liquids would boil at different temperatures owing to the difference in strength of their intermolecular forces.

The volume of water that must be added in order to dilute 40 mL of 9.0 M HCl to a concentration of 6.0 M is closest to

E) 60 ML

A sample of a compound contains 3.21 g of sulfur and 11.4 g of fluorine. Which of the following represents the empirical formula of the compound?

E) SF6

A 0.5 mol sample of He(g) and a 0.5 mol sample of Ne(g) are placed separately in two 10.0 L rigid containers at 25°C. Each container has a pinhole opening. Which of the gases, He(g) or Ne(g), will escape faster through the pinhole and why?

He(g) will escape faster because the He(g) atoms are moving at a higher average speed than the Ne(g) atoms.

Which of the following best helps explain why the pressure of a sample of CH4(g) (molar mass 16g/mol) is closer to the pressure predicted by the ideal gas law than a sample of NH3(g)(molar mass 17g/mol) ?

NH3 molecules are polar while CH4 molecules are not, and the greater attractions between NH3 molecules cause the molecules to collide with the walls of the container with less force.

The diagrams above represent two samples of gas in containers of equal volume at . Which of the following correctly compares the two samples in terms of their deviation from ideal gas behavior and explains why?

The gas in sample 2 would deviate more from ideal behavior because the Xe atoms are closer together, leading to an increase in intermolecular attractions.

Benzene, C6H6 , has the structure shown above. Considering the observation that benzene is only sparingly soluble in water, which of the following best describes the intermolecular forces of attraction between water and benzene?

There are dipole- induced dipole and London dispersion interactions between water and benzene.

The mass spectrum of element X is presentedin the diagram above. Based on the spectrum,which of the following can be concluded aboutelement X?

d) the atomic mass of 90 is between 90 and 92 d

A student has a 1 g 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

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

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

Steel is an alloy containing Fe atoms and C atoms. Which of the following diagrams best represent the particle level structure of steel?

B) The figure presents a particle diagram consisting of 12 large unshaded circles, which represent F e atoms and 6 small shaded circles, which represent C atoms. The large F e atoms are arranged in a 3 by 4 array. The small C atoms are located throughout this lattice, at every intersection of four large F e atoms.

Of the following, the best explanation for the fact that most gases are easily compressed is that the molecules in a gas

B) are relatively far apart

Which of the following is the ground-state electron configuration of the ion?

C) 1s2 2s2 2p6

Which of the following represents an electron configuration that corresponds to the valence electrons of an element for which there is an especially large jump between the second and third ionization energies? (Note: principal quantum number equal to or greater than 2.)

C) ns2 np2

A student mixes dilute AgNO3(aq) with excess NaCl to form AgCl(s), as represented by the net ionic equation above. Which of the diagrams below best represents the ions that are present in the significant concentration in the solution?

C, (2 NO3-, 2 Cl-, 4 Na+)