Question

According to MOT (molecular orbital theory), the molecular orbitals are formed by mixing of atomic orbitals through LCAO (linear combination of atomic orbitals)
The correct statement about molecular orbitals is/are;
A. Bonding of molecular orbitals are formed by addition of wave functions of atomic orbitals of the same phase
B. Anti bonding molecular orbitals are formed by subtraction of wave functions of atomic prbitals of the same phase.
C. Non bonding molecular orbitals do not take part in bond formation because they belong to inner shells
D. Anti bonding molecular orbitals provide stability to molecules while bonding molecular orbitals make the molecules unstable.

Answer 1

The given question states statements related to Mot also known as molecular orbital theory and LCAQ .i.e. linear combination of atomic orbitals so let us what these two theories are to answer the following question.

Complete step by step answer:
MOT is a theory used to describe the electronic structure of molecules by using quantum mechanics. In the Linear combination of atomic orbitals , where each molecule has a set of molecular orbitals. Assumptions were made that molecular orbital wave function $\psi {}_j$, can be simply written as weighted sum of the $n$constituent atomic orbitals $X{}_i$, acc to the following equation;
$\psi {}_j = \sum\limits_{i = 1}^n {c{}_{ij}X{}_i}$
We may determine $c{}_{ij}$coefficients numerically by substituting the given equation into the Schrödinger equation and also by applying the variational principle.
The following are three important requirements for atomic orbital combinations that is suitable as approximate molecular orbitals.
1. It should have the correct symmetry, .i.e. must belong to the correct irreducible representation of the molecular symmetry group. By using symmetry adapted linear combinations, molecular orbitals of the right symmetry are formed.
2. It should also overlap within space. They should not combine to form molecular orbitals if they are very far away from one another.
3. It must be at the same energy levels to combine as molecular orbitals.

So, the correct answer is Option A,B.

Note: Knowing both the theories will help in finding the answers easily. Please reach each option carefully not get confused between all the given options as it is similar with minute changes. MOT and LACO is a very important theories to study the electronic structure of molecules