Molecular orbitals are formed by the overlap of atomic orbitals. Two atomic called bonding molecular orbital (BMO) and anti - bonding molecular orbital (ABMO). Energy of anti - bonding molecular orbital (BMO) and anti - bonding molecular orbital ABMO). Energy of anti - bonding orbitals is raised above the parent atomic orbitals that have combined and the energy of the bonding orbital is lowered than the parent atomic orbitals. Energies of various molecular orbitals for elements hydrogen to nitrogen increase in the order : `sigma1slt sigma^(**)1s lt sigma2sltsigma^(**)2slt(pi2p_(x)~~pi2p_(y))ltsigma2p_(z)lt(pi^(**)p2p_(x)~~pi^(**)2p_(y))ltsigma^(**)2p_(z)` and for oxygen and fluorine order of energy of molecular orbitals is given as : `sigma1s lt sigma^(**)1slt sigma2sltsigma^(**)2sltsigma2p_(z)lt(pi2p_(x)~=2pi2p_(y))lt(pi^(**)2p_(x)~=pi^(**)2p_(y))ltsigma^(**)2p_(z).` Different atomic orbitals of one atom combine with those atomic orbitals of the second atom which have comparable energies and proper orientation. Further, if the overlapping is head on, the molecular orbital is called 'sigma', `(sigma)` and if the overlap is lateral, the molecular orbital is called 'pi', `(pi)`. The molecular orbitals are filled with electrons according to the same rules as followed for filling of atomic orbitals. However, the order for filling is not the same for all moleculas or their ions. Bond order is one of hte most important parameters to compare the strength of bonds.
Which of the following statements is correct?

Options

A. In the formiation of dioxygen from oxygen atoms 10 molecular orbitals will be formed.
B. All the molecular orbitals in the dioxygen will be completely filled.
C. Total number of bonding molecular orbtials will not be same as total number anti - bonding orbitals in dioxygen.
D. Number of filled bonding orbitals will be same as number of filled anti - bonding orbitals?

Explanation

To determine which statement is correct regarding the formation of molecular orbitals in dioxygen (O2), we need to analyze the formation of molecular orbitals and their filling. Here’s a step-by-step solution:

### Step 1: Understanding Molecular Orbitals in O2
When two oxygen atoms combine to form dioxygen (O2), they create molecular orbitals through the overlap of their atomic orbitals. Each oxygen atom contributes its atomic orbitals, and these combine to form bonding and anti-bonding molecular orbitals.

### Step 2: Count the Molecular Orbitals
In O2, the molecular orbitals formed are:
1. σ(1s)
2. σ*(1s)
3. σ(2s)
4. σ*(2s)
5. σ(2p_z)
6. π(2p_x)
7. π(2p_y)
8. π*(2p_x)
9. π*(2p_y)
10. σ*(2p_z)

Thus, a total of **10 molecular orbitals** are formed.

### Step 3: Filling the Molecular Orbitals
The molecular orbitals are filled according to the Aufbau principle, Hund's rule, and the Pauli exclusion principle. The filling order for O2 is:
- σ(1s) - 2 electrons
- σ*(1s) - 2 electrons
- σ(2s) - 2 electrons
- σ*(2s) - 2 electrons
- σ(2p_z) - 2 electrons
- π(2p_x) - 1 electron
- π(2p_y) - 1 electron

This results in a total of 12 electrons in the bonding orbitals and 4 in the anti-bonding orbitals.

### Step 4: Evaluating the Statements
1. **Statement 1**: "In the formation of dioxygen from oxygen atom, 10 molecular orbitals will be formed."
- **Correct** (as we counted 10 molecular orbitals).

2. **Statement 2**: "All the molecular orbitals in the dioxygen will be completely filled."
- **Incorrect** (not all are filled; π*(2p_x) and π*(2p_y) are half-filled).

3. **Statement 3**: "Total number of bonding molecular orbitals will not be the same as total number of anti-bonding molecular orbitals in dioxygen."
- **Incorrect** (there are 5 bonding and 5 anti-bonding orbitals).

4. **Statement 4**: "Number of filled bonding orbitals will be the same as number of filled anti-bonding orbitals."
- **Incorrect** (there are 5 filled bonding orbitals and 4 filled anti-bonding orbitals).

### Conclusion
The only correct statement is **Statement 1**: "In the formation of dioxygen from oxygen atom, 10 molecular orbitals will be formed."