Answer:
linear or trigonal planar
Explanation:
The molecular formula AB have the following criteria:
A= the central atom
B= directly bonded atoms.
In Molecular Geometry, Molecular Formula AB can either be Linear or Trigonal Planar.
In linear geometry, they are formed as a result of Sp hybridised orbital. Sp hybridised orbital involves blending of one s-orbital and one p-orbital to produce a hybrid orbital directed along a straight line, therefore making it linear e.g CO , HCN etc.
In Trigonal Planar, they are formed as a result of Sp hybridised orbital. Sp hybridised orbital are formed by mixing of one s-orbital and two p-orbitals to produce orbitals which are coplanar and the lobes directed towards the corners of an equilateral triangle. (Trigonal Planar) e.g BF , , SO etc.