1. how is a pair of molecular orbitals formed?
by the overlap of two atomic orbitals from the same atom
by the reproduction of a single atomic orbital
by the splitting of a single atomic orbital
by the overlap of two atomic orbitals from different atoms

Molecular orbitals are formed by the overlap of two atomic orbitals from different atoms.

Explanation:

A pair of molecular orbitals are formed by the overlap of two atomic orbitals from different atoms which are forming a molecule.

There are two parts of a molecular orbital, bonding and anti-bonding molecular orbital.

The bonding molecular orbital (BMO) are formed by the constructive interference of the atomic orbitals.

The anti-bonding molecular orbital (ABMO) are formed by the destructive interference of the atomic orbitals.

the dissociation of nickel hydroxide is follows:

the concentration of hydroxide ion is

the equilibrium constant value of nickel hydroxide is = 6.1 * 10^-^1^6 and thus equilibrium equation can be written as:

thus, concentration of ni is 0.23 * 10^-^4 mol /l