Taking into account the definition of molecular geometry, the correct option is option d.: the bond angle of a linear molecule is 180 degrees.
In first place, molecular geometry or molecular structure is the spatial distribution of atoms around a central atom. Atoms represent regions where there is a high electron density, and are therefore considered electronic groups, regardless of the bonds they form.
That is, molecular geometry is the three-dimensional arrangement of the atoms that make up a molecule.
The molecular geometry of an element characterizes some of its physical or chemical properties, such as boiling point, viscosity, and density.
Linear molecules are molecules of the AB₂ type in which the central atom does not have lone pairs. To avoid repulsions between the binding pairs, arrange the B groups as far apart as possible. For that they must oppose each other 180 °.
In summary, linear molecular geometry describes the arrangement of different atoms with 180º bonds.
So, the correct option is option d.: the bond angle of a linear molecule is 180 degrees.
Learn more about molecular geometry with this example:
