CARBON AND ITS COMPOUNDS (CBSE 10TH CHEMISTRY IMPORTANT QUESTIONS REPEATED)

 

1. What is the valency of carbon?

The valency of carbon is 4. Carbon has 4 electrons in its outermost shell and needs 4 more to complete its octet. Therefore, it forms four covalent bonds with other atoms.

2.Give the IUPAC name of CH₃CH₂OH?

The IUPAC name of CH₃CH₂OH is Ethanol.

It is an alcohol with a two-carbon chain (ethane) and an –OH functional group, hence the name ethanol.

3. What is catenation?

Catenation is the ability of an element to form bonds with atoms of the same element, forming chains or rings. Carbon shows a strong tendency for catenation, allowing it to form long chains, branched structures, and rings due to the strong C–C bonds.

4. Draw the electron dot structure of ethene (C₂H₄)?

Molecular formula: C₂H₄

Ethene contains:

• 2 carbon atoms connected by a double bond (C=C)

• 4 hydrogen atoms, each forming a single covalent bond with carbon

• Electron Dot Structure:

•   H       H

       \     /

     C = C

      /     \

   H       H

5. What are homologous series? Give one example.

A homologous series is a group of organic compounds having the same functional group, similar chemical properties, and a general formula, where each successive member differs by a –CH₂– group (i.e., 14 amu).

Example:
The alkane series:
Methane (CH₄), Ethane (C₂H₆), Propane (C₃H₈), Butane (C₄H₁₀), etc.

6. Why do carbon compounds have low melting and boiling points?

Carbon compounds (especially covalent compounds) have low melting and boiling points because:

• They are held together by weak intermolecular forces (van der Waals forces).

• They do not have strong ionic or metallic bonds that require more energy to break.