Question

Assertion (A): Carbon shares its valence electrons with other atoms of carbon or with atoms of other elements.
Reason (R): The shared electrons belong to the outermost shells of both the atoms and lead to both atoms attaining the noble gas configuration.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.

Hint:

Covalent bonding in carbon:

• Carbon shares electrons (not transfers) due to its 4 valence electrons.
• Sharing allows both atoms to achieve noble gas configuration (octet rule).
• This explains why carbon forms millions of compounds (catenation and tetravalency).

Answer 1

The Correct Option is A

Step 1: Analyze Assertion (A).
Assertion (A): "Carbon shares its valence electrons with other atoms of carbon or with atoms of other elements."

• Carbon has 4 valence electrons (electronic configuration: 2,4).
• It cannot lose 4 electrons to form C⁴⁺ (requires too much energy).
• It cannot gain 4 electrons to form C⁴⁻ (difficult for nucleus to hold 10 electrons).
• Therefore, carbon achieves stability by sharing its valence electrons through covalent bonding.
• Carbon forms covalent bonds with other carbon atoms (e.g., in diamond, graphite, hydrocarbons) and with atoms of other elements (e.g., H, O, N, Cl).
• Assertion (A) is TRUE.

Step 2: Analyze Reason (R).
Reason (R): "The shared electrons belong to the outermost shells of both the atoms and lead to both atoms attaining the noble gas configuration."

• In covalent bonding, atoms share pairs of electrons.
• Each shared electron pair contributes to the outermost shell of both atoms.
• By sharing electrons, each atom effectively completes its octet (or duplet for hydrogen) and attains the stable electron configuration of the nearest noble gas.
• Example: In CH₄, carbon shares electrons with four hydrogen atoms, achieving 8 electrons in its valence shell (neon configuration).
• Reason (R) is TRUE.

Step 3: Check if Reason (R) correctly explains Assertion (A).

• Carbon shares its valence electrons BECAUSE by doing so, both atoms (carbon and the other atom) achieve noble gas configuration.
• The driving force for sharing electrons is precisely to attain stability through noble gas configuration.
• Thus, Reason (R) is the correct explanation of Assertion (A).

Final Answer: (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).