The graph between $$|\psi|^2$$ and r (radical distance) is shown below. This represents:

• For an s-orbital, the radial wave function has a maximum, non-zero value at the nucleus.
• For p, d, and f orbitals, the wave function value at the nucleus is always zero because of the angular nodes 
• Looking at the graph, the curve starts at a very high value on the y-axis when r = 0, meaning it must be an s-orbital.

2. Finding the Number of Radial Nodes

• A radial node is a region in space where the probability of finding an electron drops exactly to zero..
• In the given graph, the curve touches the x-axis exactly once before rising again and gradually tapering off to infinity.
• Therefore, the number of radial nodes = 1.

3. Determining the Principal Quantum Number 

The formula to calculate the number of radial nodes for any given orbital is:

Radial Nodes = n - l - 1

Where:

• n = Principal quantum number
• l = Azimuthal quantum number (for an s-orbital, $l = 0$)

Substituting our known values into the equation:

1 = n - 0 - 1 = 2