Test: Molecular Orbital Theory - Chemistry MCQ

Paramagnetic molecules are attracted by the magnetic field and orbitals are singly occupied. O₂ is an example. Whereas diamagnetic molecules are repelled by the magnetic field, so the option is wrong.

The formula of bond order is given by 1⁄2(N_B – N_A) When NB is bonding orbitals and N_A is the number of anti-bonding orbitals. In Oxygen, bond order = 1/2(10-6) = 2. When it’s zero the molecule cannot be formed.

An electron that enters bonding orbitals stabilizes the molecule as it’ in between two nuclei. Whereas when an electron is entered into the anti-bonding orbital, it needs to pull an electron away from the nucleus.

Combining atomic orbitals must have symmetry as per molecular axis is true. The corrected statements are combining atomic orbitals must have equal energy, must overlap to the maximum extent and Z-axis should be taken as the molecular axis.

As the stability increases, the energy of that substance decreases. The higher the energy, the less stable the molecule. So stability is inversely proportional to the energy. This can be seen in any part of the universe.

F. Hund and R.F. Mullikan proposed Molecular orbital theory in the year 1932. According to this theory, the combination of two atomic orbitals results in the formation of two molecular orbitals namely one bonding and one anti-bonding orbital.

The bond length has defined the distance between two atoms in a molecule. The bond order depends on the bond length between two atoms in a molecule. As the bond length increases the bond decreases and vice-versa.

When a molecule consists both bonding molecular orbitals and anti-bonding molecular orbitals, the higher the number of bonding orbitals, the more the bonding influence and the more stable the molecule will be and vice-versa.

According to the nomenclature, sigma molecular orbitals are symmetrical around the bonding axis and the pi molecular orbitals are not symmetrical around the bonding axis. So the given statement is false.

The linear combinations like additions and subtractions of wave functions of individual atomic orbitals indicate the formation of molecules mathematically, as given i.e. ψ_MO = ψ_A + ψ_B. Where ψ represents the wavefunctions of atomic orbitals.