Name the functional group present in each of the following compounds:
(i) HCOOH
(ii) C2H5CHO
(i) HCOOH
(ii) C2H5CHO
Write the next homologue of each of the following:
i) C2H4
ii) C4H6
i) C2H4 is an alkene name is an ethene. Its next homologue is obtained by adding a -CH2- unit. Thus the name of next homologue is propene C3H6.
ii) C4H6 is an alkyne; the homologue name is butyne. Its next homologue is obtained by adding -CH2- unit and thus the name homologue next is pentyne
Define homologous series of organic compounds. List its two characteristics. Write the name and formula of the first member of the series of alkenes.
For example, methane, ethane, propane, butane, etc. are all part of the alkane homologous series.
Methane CH4
Ethane CH3CH3
Propane CH3CH2CH3
Butane CH3CH2CH2CH3
There is a difference of −CH2 unit between each successive compound.
Characteristics of homologous series:
All the members of the homologous series have same functional groups and hence similar chemical properties.
Two successive members of a homologous series differ by a −CH2 unit.
Ethene is the first member of the series of alkenes. Its formula is C2H4.(a) Define the term 'isomers'.
(b) Draw two possible isomers of the compound with molecular formula C3H6O and write their names.
(c) Give the electron dot structures of the above two compounds.
(a) Isomers are the molecules having same molecular formula but different structural formula.
(b) Two possible isomers of the compound with molecular formula C3H6O are acetone and propanal:
(c) Electron dot structure of these compounds is: 
What are the covalent compounds? why are they different from ionic compounds? List their three characteristic properties.
| Covalent Bonding | Ionic Bonding |
| A covalent compound is formed by the mutual sharing of electrons to complete the octet of the shell. For example, O2 is formed by the covalent bonding. |
In the ionic bonding, the transfer of electron takes place. In this bonding, one electron donor and one electron acceptor are required. For example NaCl. |
 |
 |
| i) They have low melting. | They have high melting. |
| ii) They do not conduct electricity | They conduct electricity |
| iii) They have definite shape | They do not have a definite shape. |
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