Question

Given the formula representing a molecule:

H – C (tripple bond) C – H


The molecule is


A) symmetrical and polar

B) symmetrical and nonpolar

C) asymmetrical and polar

D) asymmetrical and nonpolar

Answer 1

Symmetrical and non polar

Step-by-step explanation:

H- C = C- H is a symmetrical, non polar molecule since it is linear and the arrangement of the atoms is the same on both sides of the triple bond.

Answer 2

B) Symmetrical and nonpolar

Step-by-step explanation:

The formula is H-C≡C-H.

Each C atom has two electron regions, so VSEPR theory predicts a linear molecular geometry (see image below).

The molecule is symmetrical, because the green line divides the molecule into two halves that are mirror images of each other.

The C-H bonds are slightly polar, because C is more electronegative than H (µ ≈ 0.4 D).

The C atoms are partially negative (red), while the H atoms are partially positive (blue).

However, the two C-H bond dipoles point in opposite directions, so they cancel each other. The molecule has no net dipole moment.

Acetylene is nonpolar.