Considering X-axis as the internucler axis, which out of the following atomic orbitals will from a sigma bond ?
`(a)1sand 1s" " (b) 1s and 2p_(x)" "(c )2p_(y)and2p_(y)" "(d)1s and2s.`

Explanation

To determine which atomic orbitals will form a sigma bond when considering the X-axis as the internuclear axis, we will analyze each option step by step.

### Step 1: Understanding Sigma Bonds
A sigma bond is formed when two atomic orbitals overlap along the internuclear axis. This overlap can occur between:
- Two s orbitals
- An s orbital and a p orbital (where the p orbital is oriented along the internuclear axis)
- Two p orbitals that are oriented along the internuclear axis (e.g., p_x with p_x)

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