The wave functions of Is-orbitals of two hydrogen atoms are ` Psi_(A) " and " Psi _(B) . Psi_(A) " and " Psi_(B)` are linearly combine to form two molecular orbitals `( sigma " and " sigma^(**))` . Which of the following statements are correct ?
I . ` sigma^(**)` equal to ` (Psi_(A) - Psi_(B))` .
In ` sigma` - orbital, one nodal plance is present in between two nuclei .
III. The energy of ` sigma`-orbital is lower then the energy of `sigma`-orbital .

Options

A. I,II,III
B. I,II only
C. II,III only
D. I, III only

Answer

D

Explanation

According to molecular orbital theory:
I ` sigma^(**)`-orbital are formed by the substraction of two wave functions say `Psi_(A) - Psi_(B)`.
II . `sigma` - orbital are formed when two orbitals are in same phase and thus , do not have nodal plane in between two nuclei .
III. Combination of two sigma `(sigma)` atomic orbitals given two molecular orbitals , out of which one is of lower energy called ` sigma ` bonding orbital and other is f higher energy called ` sigma^(**)` anti-bonding orbital . Hence , (i) and (iii) are the correct statements and option (d) is the correct answer .