Organic Chemistry Basics Result Question 20
20. In allene $\left(\mathrm{C} _3 \mathrm{H} _4\right)$, the type(s) of hybridisation of the carbon atoms, is (are)
(2012)
(a) $s p$ and $s p^3$
(b) $s p$ and $s p^2$
(c) only $s p^3$
(d) $s p^2$ and $s p^3$
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Answer:
Correct Answer: 20. ( b )
Solution:
- Allene is the name given to propdiene, $\mathrm{H} _2 \mathrm{C}$ C $\mathrm{CH} _2$.
Hybridisation of an atom is determined by determining the number of hybrid orbitals at that atom which is equal to the number of sigma $(\sigma)$ bonds plus number of lone pairs at the concerned atom. $\operatorname{Pi}(\pi)$ bonds are not formed by hybrid orbitals, therefore, not counted for hybridisation.
Here, the terminal carbons have only three sigma bonds associated with them, therefore, hybridisation of terminal carbons is $s p^3$. The central carbon has only two sigma bonds associated, hence hybridisation at central carbon is $s p$.
BETA
