31.How many constitutional isomers are there for C5H11Br?
(A)3
(B)7
(C)8
(D)10
(E)11.

27.Diastereomers have the same (A)melting point. (B)reaction rate toward optically active reagent. (C)molecular weight. (D)stereochemistry at each chiral center. (E)specific rotation.

28.Which of the following statements is correct? (A)A structure with two chiral centers will always give rise to four stereoisomers (B)Molecules that contain chiral carbons must be optically active compounds. (C)Equimolar mixtures of two enantiomers are called racemate. (D)Distereomers have same physical properties. (E)none of the above.

29.Who characterized alpha, beta and gamma radiation? (A)Thomson (B)Einstein (C)Rutherford (D)Heisenberg (E)Bohr

30.Of the following sets of four quantum numbers, identify the ones that can exist for an electron in an atom? (A)(5, 4, 5, +1/2) (B)(2, 2, -1, +1/2) (C)(3, 2, 2, +1/2) (D)(6, 7, 0, +1/2) (E)(2, 0, -2, +1/2)

32.Which of the following statements correctly describes an achiral molecule? (A)The molecule has a nonsuperimposable mirror image. (B)The molecule exhibits optical activity when it interacts with plane-polarized light. (C)The molecule has an enantiomer. (D)The molecule might be a meso form. (E)None of the above.

33.Which of the following molecules has the highest bond order? (A)BN (B)CO (C)NO (D)Ne2 (E)F2

34.According to the VSEPR theory, which of the following statements is correct? (A) The expected geometry of TeO32- is trigonal planar. (B) The expected geometry of SbBr 4 3- is tetrahedral. (C) The expected geometry of SeS24- is bent. (D) The expected geometry of BiCl3 is pyramidal. (E) The expected geometry of SnI42- is square planar.

複選題35.Which of the following statements is correct? (A)In O2, O22- , O2- , and O2+ species, only the O22- molecule is diamagnetic. (B)The stability decreases in the order O2+ > O2 > O2 - >O2 2- (C)The dissociation energy of N2 is larger than that of N2 + , while the dissociation energy of C2+ is smaller than that of C2. (D)In Mn2+, Cr3+, Hg2+ , V 3+, Ni2+, and La3+ six transition metal ions, only Mn2+ , V 3+, and La3+ are paramagnetic. (E)The atom size increases in the order K+ > Cl- > S2- , while the atom size of Au+ is larger than that of Au3+ .

36.Which of the following atoms is paramagnetic? (A)Cd (B)Tl1- (C)Nb1+ (D)Ni (E)Ru1+

複選題37.Which of the following statements is not true? (A)trans-1,3-dimethylcyclohexane is more stable than cis –1,3-dimethylcyclohexane. (B)trans-1,2-dimethylcyclohexane is more stable than cis–1,2-dimethylcyclohexane. (C)trans-1,4-dimethylcyclohexane is more stable than cis–1,4-dimethylcyclohexane. (D)trans-1,2-dimethylcyclohexane is more stable than cis–1,3-dimethylcyclohexane. (E)trans-1,2-dimethylcyclohexane is less stable than cis–1,3-dimethylcyclohexane.