Exams › JEE Main › Chemistry
Which of the following molecules contains the shortest C=C double bond?
- CH2=C=CH2
- CH3-CH=CH2
- CH3-C(CH3)2-CH=CH2
- CH3-C(CH3)=CH2
Correct answer: CH2=C=CH2
Solution
Greater s-character in the hybrid orbitals pulls bonding electrons closer to the nuclei, shortening the bond. In allene (CH2=C=CH2) the central carbon is sp hybridised (50% s-character) while the terminal carbons are sp2. The C=C bonds in allene are therefore shorter than the sp2-sp2 C=C bonds in the ordinary alkenes (options 2, 3, 4). Hence allene has the shortest C=C bond.
Related JEE Main Chemistry questions
- Although the electronegativity gap between N and F is larger than that between N and H, ammonia has a dipole moment of 1.5 D while nitrogen trifluoride has only 0.2 D. The reason is that
- When N₂ is converted into N₂⁺, the dissociation energy of the N–N bond ______, and when O₂ is converted into O₂⁺, the dissociation energy of the O–O bond ______.
- From the ions listed below, which pair has geometries that can be accounted for by the same type of orbital hybridization? NO₂⁻, NO₃⁻, NH₂⁻, NH₄⁺, SCN⁻
- Atoms A and B have electronegativities of 1.20 and 4.0, respectively. What is the percentage ionic character of the A–B bond?
- In the phosphate ion, PO₄³⁻, what is the formal charge on an oxygen atom that is singly bonded to phosphorus in a P–O bond?
- Among the following species, which one has no unpaired electrons?
⚔️ Practice JEE Main Chemistry free + battle 1v1 →