Question

Double bond equivalent of ${C_4}{H_6}$ is:
A. 0
B. 1
C. 2
D. 3

Answer 1

The double bond equivalent is a method used to determine the number of pi-bonds and the number of rings present in the compound. The molecular formula does not determine the number of pi-electron systems or the presence of rings in the structure of the compound.

Complete step by step answer:
The double bond equivalent provides a formula that is used in organic chemistry to determine whether the compound has any pi-bonds or rings in it or not and ultimately to draw chemical structures. It does not give any information about those components individually which include the specific number of rings, or of double bonds (one $\pi$ bond each), or of triple bonds (two $\pi$ bonds each). The formula for double bond equivalent is:
$DBE = C - \dfrac{H}{2} - \dfrac{X}{2} + \dfrac{N}{2} + 1$
Where, C = number of carbon atoms present
H = number of hydrogen atoms present
X = number of halogen atoms
N = number of nitrogen atoms
In the compound, ${C_2}{H_4}$ , there are only two carbon atoms and four hydrogen atoms in the compound. Thus, the double bond equivalent can be determined as:
$DBE = 4 - \dfrac{6}{2} - 0 + 0 + 1 = 2$
Thus, it means that the compound may have two $\pi - bond$ or a ring like closed chain structure. The minimum number of carbon atoms required to form a ring is 3. Hence, this implies that it has the possibility to form both.

So, the correct answer is Option C .

Note:
The final structure of the compound is verified with the use of nuclear magnetic resonance spectroscopy, mass spectrometry and infrared spectroscopy, as well as the qualitative analysis of the resultant compound. The spectroscopy is a method of determining the positions of various bonds, atoms, substituents and most important, the functional groups present in the compound with the help of various chemicals and electromagnetic radiations.