Alkanes have only single bonds between carbon atoms

Steps:

• Recall that alkanes are hydrocarbons with the general formula CₙH₂ₙ₊₂ and only single C-C and C-H bonds.
• Examine each option for the presence of double or triple bonds, which indicate unsaturation.
• Identify the option with exclusively single bonds and matching the alkane formula.
• Confirm the structure aligns with a straight-chain alkane.

Why B is correct:

• CH₃CH₂CH₃ is propane (C₃H₈), fitting the alkane formula CₙH₂ₙ₊₂ with all single bonds.

Why the others are wrong:

• A: CH₃CH=CH₂ has a C=C double bond, making it an alkene (propene, C₃H₆).
• C: CH₂=CH₂ has a C=C double bond, making it an alkene (ethene, C₂H₄).
• D: (CH₃)₂C=CH₂ has a C=C double bond, making it an alkene (2-methylpropene, C₄H₈).

Final answer: B