Question

Let's assume the $C^{1} \equiv C^{2}$ bond in acetylene is along zaxis. Find out the correct combination of atomic orbitals with non-zero overlapping.

• A. $2 P_{x}$ of $C ^{1}$ and $2 P_{y}$ of $C ^{2}$
• B. $2 P_{z}$ of $C^{1}$ and $2 P_{y}$ of $C^{2}$
• C. $2 P_{x}$ of $C ^{1}$ and $2 S$ of $C ^{2}$
• D. $2 P_{z}$ of $C^{1}$ and $2 P_{z}$ of $C^{2}$

Answer 1

Answer: (D)

In acetylene, we have $2 p_{z}$ of $C_{1}$ and $2 p_{z}$ of $C_{2}$ along $z$-axis, because both orbitals are $p$-orbitals and are in same direction, i.e. $z$-direction.
The formula of acetylene is $CH \equiv CH$.