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Question
Write the molecular formula of the 2nd and 3rd member of the homologous series where the first member is ethyne.
Solution
The general formula for the homologous series whose first member is ethyne is CnH2n - 2.
The two consecutive members (2nd and 3rd) of this series are:
a. CH3C≡CH (Propyne); where n is 3
b. CH3CH2C≡CH(1-Butyne) or CH3C≡CCH3 (2-Butyne); where n is 4
The molecular formulae are C3H4 and C4H6, respectively.
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RELATED QUESTIONS
What is a homologous series?
Write the next homologue of the following: C2H4
Complete the following table which relates to the homologous series of hydrocarbons.
|
General Formula |
IUPAC name of the homologous series | Characteristic bond type | IUPAC name of the first member of the series |
| `C_nH_(2n-2)` | (A)________ | (B)______ | (C)______ |
| C_nH_(2n+1) | (B)________ | (E)______ | (F)______ |
An organic compound having the molecular formula C3H6O can exist in the form of two isomers A and B having different functional groups. The isomer A is a liquid which is used as a solvent for nail polish. The isomer B is also a liquid. An aqueous solution of one of the lower homologues of B is used for preserving biological specimens in the laboratory
(a) What is compound A?
(b) Write the electron-dot structure of A.
(c) What is compound B?
(d) Write the electron-dot structure of B.
(e) Name the lower homologue of compound B which is used in preserving biological specimens.
Give the structure of the second member of the alcohol group
Study the different conclusions drawn by students of a class on the basis of observations of preserved/available specimens of plants and animals.
I. Potato and sweet potato are analogous organs in plants.
II. Wings of insects and wings of birds are homologous organs in animals.
III. Wings of insects and wings of bats are analogous organs in animals.
IV. Thorns of citrus and tendrils of cucurbita are analogous organs in plants.
The correct conclusions are:
(A) I, and II
(B) II and IV
(C) I and III
(D) III and IV
Write the name and formula of the fourth member of the following homologous series:
Alkyne
What is a homologous series?
The unsaturated hydrocarbons containing a carbon-carbon double bond are called _______.
As one ascends in any homologous series, physical properties change gradually.
