Dear Candidates Solve the MCQS But we are not giving Answers 1) A superconducting compound A) loses its resistance at a critical temperature, and becomes magnetic. B) has very high ionic conductivity, and low electronic conductivity. C) loses its resistance and excludes the magnetic flux from its interior below a critical temperature Tc. D) has potential applications for fuel cells. E) has very high resistivity above a certain temperature. 2) In a ferromagnetic material A) the magnetic moment is very large, because the localized spins of the constituting atoms/ions become oriented in the same direction upon application of an external magnetic field. B) the magnetic moment is very small, because the localized spins of the constituting atoms/ions in alternating planes become oriented in the opposite direction upon application of an external magnetic field. C) the magnetic moment is negligible, as the magnetic domains are randomly oriented below the transition temperature, or Curie temperature. D) a transition occurs below the Neel temperature to a disordered magnetic state. E) none of the above. 3) A charge transfer band refers to A) a forbidden weak absorption band in the optical spectra corresponding to a ligand-to-metal, or a metal-to-ligand transition. B) a strong absorption band in the optical spectra corresponding to a ligand-to-metal, or a metal-to-ligand transition. C) a spin forbidden transition. D) a Laporte-forbidden band that is observed because of distortions due to molecular vibrations. E) a band, usually in the UV, in transition metal complexes with the transition metal ion in zero, or low formal oxidation states. 4) The structure of ZrO2, which when doped with Y3+ or Ca2+ is an oxide ion conductor and commercially used as an oxygen sensor, is best described as: A) cubic close packing of oxygens and the Zr(IV) ions filling all the octahedral holes. B) cubic close packing of oxygens and the Zr(IV) ions filling half of the tetrahedral holes. C) cubic close packing of the Zr(IV) ions and oxygen occupying all of the tetrahedral holes. D) cubic close packing of the Zr(IV) ions and oxygen occupying the octahedral holes. E) none of the above. 5) Concerning ionic radii, it is true that A) small ionic radii favor large coordination number. B) the least water-soluble salts are those of ions with similar radii. C) species with high oxidation numbers are stabilized by large anions. D) small cations stabilize large anions. E) the decomposition temperature of thermally unstable compounds increases with decreasing cation radius. 6) The lattice enthalpy A) can be experimentally determined by the Born-Haber cycle and theoretically calculated from the Born-Mayer equation. B) is directly proportional to the effective size of the constituent ions. C) is directly proportional to the Madelung constant, which is a function of the interionic distances. D) can be experimentally determined by the Born-Mayer equation. E) is independent of the structure of the compound. 7) The experimentally determined magnetic moment of the complex [Fe(H2O)6]3+ is 5.9 μB. This indicates that the electronic configuration of the Fe ion is: A)t2g4eg0 B)t2g3eg1 C)t2g4eg1 D) t2g3eg2 E)t2g5eg0 8) The common ores of nickel and copper are sulfides, while those of iron and aluminum are oxides this is a manifestation A) of the historical development of the earth’s crust. B) that Ni2+ and Cu2+ are hard acids and Al3+ and Fe3+ are soft acids. C) that Ni2+ and Cu2+ are soft acids, Al3+ and Fe3+ are hard acids, and S2- is a soft base and O2- is a hard base. D) that Ni2+ and Cu2+ are soft acids, Al3+ and Fe3+ are hard acids, and S2- is a hard base and O2- is a soft base. E) none of the above. 9) Aluminum chloride forms a dimer in the vapor phase with the molecular formula, Al2Cl6, because A) of strong π bonding between Al and Cl p orbitals. B) the formation of self acid-base complex between the Lewis acid AlCl3 and the Lewis base, AlCl3. C) the formation of self acid-base complex between two Lewis acid AlCl3 molecules and a Lewis base, Cl one from each of the AlCl3. D) Al is a hard acid and Cl is a soft base. E) Al is a hard acid and Cl is a hard acid. 10) When TiO2 is heated in hydrogen, a blue color develops, indicating that A) reduction of Ti(IV) to Ti(III) occurred, with the impurity levels just above the valence band, leading to p-type conductivity B) reduction of Ti(IV) to Ti(III) occurred, with the impurity levels just below the conduction band, leading to n-type conductivity, and excitation of electrons in the visible by absorption of red light C) oxidation of Ti(IV) to Ti(V) occurred, with the impurity levels just above the valence band, leading to n-type conductivity, and excitation of electrons in the visible by absorption of blue light D) reduction of Ti(IV) to Ti(III) occurred, with the impurity levels just below the conduction band, leading to p-type conductivity, and excitation of electrons in the visible by absorption of red light E) reduction of Ti(IV) to Ti(III) occurred, with the impurity levels just above the valence band, leading to n-type conductivity, and excitation of electrons in the visible by absorption of red light
Posted on: Sat, 15 Jun 2013 13:06:40 +0000
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