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.

【已刪除】複選題23.How many valence electrons in an element can have for each of the following species? (choosing the correct answers) (I)P3+ (II)Rh2+ (III)Co4+ (IV)Mn3+ (V)Ni2+ (VI)Si2+ (VII)Sb (VIII)B1+ (AB)(I) + (III) = 8e- (AC)(II) + (VI) = 8e- (AD)(III) + (VII) = 9e- (AE)(I) + (IV) + (VIII) = 6e- (BC)(II) + (V) + (VII) = 18e-(BD)無答案

24.Which of the following statements is not correct? (A)According to the VSEPR theory, the I3- molecule is predicted to be linear. (B)According to the VSEPR theory, the InF4 1- molecule is predicted to be tetrahedral. (C)According to the VSEPR theory, the GeBr 3 1- molecule is predicted to be trigonal planar (D)According to the VSEPR theory, the C1I3 molecule is predicted to be T-shaped. (E)According to the VSEPR theory,TeS3 2- molecule is predicted to be pyramidal.

25. Suppose the hypothetical set of quantum numbers:n = 1, 2, 3, ……l = 0, 1, 2, 3, …… , n–1mₗ = 1s = 1/2, –1/2then which of the following statements is not correct?(A) There is one s orbital, one p orbital, and one d orbital.(B) The atomic number of the first element in the d orbital-filler is 12.(C) There are two transition elements in the first period.(D) The atomic number of the first inert gas is 2.(E) If one element has the atomic number 14, then its electron configuration is 1s²2s²2p³3s²3p².

26.Arrange in decreasing order of stability of the following four isomers. (I)cis-1-chloro-2-methylcyclohexane (II)trans-1-chloro-2-methylcyclohexane (III)cis-1-chloro-3-methylcyclohexane (IV)trans-1-chloro-3-methylcyclohexane (A)(II) > (III) > (I) > (IV) (B)(I) > (II) > (IV) > (III) (C)(III) > (II) > (IV) > (I) (D)(IV) > (II) > (I) > (III) (E)none of the above.

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)

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

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