急~CHEM. MC

Kyy010203

2010-11-04 7:04 am

Question 1:
The element carbon
(1) has four electrons in the outermost shell of its atoms.
(2) can form molecules containing many carbon atoms linked together in
chains.
(3) can form compounds having the general formula CnH2n containing single
bonds only.
A. (1) only
B. (1) and (2) only
C. (2) and (3) only
D. All of them
Question 2:
The members of homologous series
(1) can be represented by a general formula.
(2) generally have similar chemical properties.
(3) need not have the same functional groups.
A. (1) and (2) only
B. (1) and (3) only
C. (2) and (3) only
D. All of them
Question 3:
Which of the following statements about alkenes are correct?
(1) They contain a double bond in their structures.
(2) They burn to form carbon dioxide only on complete combustion.
(3) They can be represented by the general formula CnH2n.
A. (1) and (2) only
B. (1) and (3) only
C. (2) and (3) only
D. All of them
Question 4:
In a homologous series, which of the following would decrease as the number of
carbon atoms increases?
A. van der Waals’ forces
B. melting point
C. solubility in water
D. densities
2
Question 5:
In a homologous series of organic compounds, as the molecular masses of the
members increase, there will be an increase in
(1) molecular size.
(2) molar volume.
(3) the ease of evaporation.
A. (1) only
B. (2) only
C. (2) and (3) only
D. All of them
Question 6:
Which of the following pairs of compounds belong to the same homologous
series?
(1) C2H4 and C4H8
(2) CH3COOH and HCOOH
(3) C2H5OH and C4H9OH
A. (1) only
B. (2) only
C. (2) and (3) only
D. All of them
Question 7:
Which of the following sets of four numbers represents the molecular masses of four
consecutive members of a homologous series of organic compounds?
(Relative atomic masses: H=1; C=12; O=16)
A. 28, 30, 32, 34
B. 28, 38, 48, 58
C. 28, 40, 52, 64
D. 28, 42, 56, 70
Question 8:
Which of the following is NOT an organic compound?
A. CHCl3
B. NaC2O4
C. Na2CO3
D. CH3COONa

回答 (1)

己式庚辛

2010-11-04 10:12 am

✔ 最佳答案

1. B or D
(1) is correct: electronic configuration of carbon is 2,4
(2) is correct. carbon has strong ability of catenation, i.e. forming long chains, owing to the bond energies.
(3)... what level are you in? chemicals with general formula of CnH2n is alkene, which consists of C=C bond. ------ however, cycloalkanes also have general formula of CnH2n, but contain NO double bonds.

2. A
(1) & (2) are straight forward. however, compounds in same group must have same functional group.

3. B
alkenes contain C=C bond. however, upon combustion it al least form carbon dioxide AND water.

4. C
as length of alkyl group increases, the compound becomes less polar, thus is less water-soluble.

5. A
increasing no. of -CH2- means molecular size increases.
molar volume of ALL gaseous compounds are the same. it's 24dm^3 per mole at room temp. and pressure.
increasing molecular size, increasing van der waal's force, less likely to overcome the intermolecular attraction ----> less volatile, less likely to evaporate.

6. C or D
(1) is alkene (or cycloalkane...)
(2) is alkanoic acid (let's not consider the alkanal group at this moment)
(3) is alkanol

7. D
each member differs by a -CH2- group; formula mass of -CH2- is 14. thus each consecutive member, in molecular mass, differs by 14.

8. C
metal carbonates are not considered as organic. others are carbon dioxide, carbon monoxide, metal hydrogencarbonates. carbides and cyanides are NOT organic neither.

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