Question

3 mark for review lewis diagrams of molecules of three different hydrocarbons are shown above. which of the following claims about the molecules is best supported by the diagrams? a all the atoms in molecule 1 lie in one plane. b all the molecules have the same empirical formula. c the c-c-c bond angle in molecule 2 is close to 180°. d the strongest carbon-to-carbon bond occurs in molecule 3.

Explanation:

• Option A: Molecule 1 has single C - C bonds (alkane - like, propane). Carbon atoms with four single bonds have tetrahedral geometry, so atoms don't lie in one plane. Eliminate A.
• Option B: Empirical formula is simplest ratio. Molecule 1: \(C_3H_8\) (empirical \(C_3H_8\)), Molecule 2: \(C_3H_6\) (empirical \(CH_2\)), Molecule 3: \(C_3H_4\) (empirical \(C_3H_4\)). Different empirical formulas. Eliminate B.
• Option C: Molecule 2 has a double C - C bond (alkene - propene). The carbon with double bond has trigonal planar geometry around it, but the C - C - C bond angle in propene is around 120°, not 180°. Eliminate C.
• Option D: Bond strength: triple bond > double bond > single bond. Molecule 3 has a triple C - C bond, so it has the strongest C - C bond among the three. This claim is supported.

Answer:

D. The strongest carbon - to - carbon bond occurs in molecule 3.