Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :
- Both Statement I and Statement II are true
- Both Statement I and Statement II are false
- Statement I is true but Statement II is false
- Statement I is false but Statement II is true
Answer
(4) Statement I is false but Statement II is true
Solution
Statement I:
Decarboxylation: CH3COONa + NaOH [ ]CaO CH4 + Na2CO3 ⇒ methane
Kolbe's electrolysis: 2CH3COO-Na+ + 2H2O electrolysis CH3-CH3 + 2CO2 + H2 + 2NaOH ⇒ ethane, not methane
Grignard reagent: CH3MgBr + H2O CH4 + Mg(OH)Br ⇒ methane
⇒ Statement I is false.
Statement II: hydrogenation of the smallest unsaturated hydrocarbons (ethene, ethyne) gives ethane, and the Wurtz reaction joins two alkyl groups ( 2CH3Br + 2Na dry ether CH3-CH3 + 2NaBr)
⇒ both give alkanes with at least two carbon atoms; as per NCERT, methane cannot be prepared by these methods ⇒ Statement II is true.
Answer: (4)