The state of hybridization of C₂, C₃, C₅ and C₆ of the

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The molecule shown in the image contains four carbon atoms of interest: C₂, C₃, C₅ and C₆. Their hybridization can be deduced by looking at the type and number of bonds each carbon forms.

C₂: In the diagram C₂ is attached to a triple bond (‒≡‒) with the neighboring carbon. A carbon involved in a triple bond uses one σ‑bond and two π‑bonds, requiring two hybrid orbitals for σ‑bonding and one unhybridized p‑orbital for each π‑bond. This corresponds to $sp$ hybridization.

C₃: C₃ is shown forming four single σ‑bonds (to three other atoms and to a hydrogen). Four σ‑bonds arise from four equivalent sp³ hybrid orbitals, so C₃ is $sp3$ hybridized.

C₅: C₅ participates in a double bond (‒=‒). A double bond consists of one σ‑bond and one π‑bond, which is produced by mixing one s orbital with two p orbitals, giving three hybrid orbitals. Hence C₅ is $sp2$ hybridized.

C₆: C₆ forms only single σ‑bonds (to two carbons and two hydrogens). As with C₃, four σ‑bonds mean the carbon uses four sp³ hybrid orbitals. Therefore C₆ is $sp3$ hybridized.

Summarizing the hybridizations in the order presented (C₂, C₃, C₅, C₆) gives:

$sp,\; sp3,\; sp2\backslash ;\; and\; \backslash ;\; sp3$.