Question

Which of following molecules is not linear?

• A. $\text{O}=\text{C}=\text{C}=\text{C}=\text{O}$
• B. ${\text{H}}_{\text{2}}\text{C}=\text{C}=\text{O}$
• C. $\text{HC}\equiv \text{C}-\text{C}\equiv \text{CH}$
• D. $\text{HC}\equiv \text{CH}$

Answer 1

The correct option is B ${\text{H}}_{\text{2}}\text{C}=\text{C}=\text{O}$

(A) $\text{O}=\underset{\text{SP}}{\text{C}}=\underset{\text{SP}}{\text{C}}=\underset{\text{SP}}{\text{C}}=\text{O}$
Eery carbon has two bond-pair of electrons.
A/C VSEPR theory, SP hybridized molecule is linear.
Hence, option (A) is linear.
(B) $\underset{\text{SP}}{\text{C}{\text{H}}_2}=\underset{\text{SP}}{\text{C}}=\text{O}$
The terminal carbon is $\text{S}{\text{P}}^2$ hybridized which means carbon has three bond pair of electrons. Since, $\text{S}{\text{P}}^2$ hybridized carbon is not linear.
Hence, option (B) is not linear.
(C) $\underset{\text{SP}}{\text{CH}}\equiv \underset{\text{SP}}{\text{C}}-\underset{\text{SP}}{\text{C}}\equiv \underset{\text{SP}}{\text{CH}}$
Every carbon is SP hybridized. Hence, option (C) is linear.
(D) $\underset{\text{SP}}{\text{CH}}\equiv \underset{\text{SP}}{\text{C}}$
Every carbon is SP hybridized. Hence, Option (D) is linear.
Option (B) is correct answer.