Which of the following is the correct plot for the probability density 2(r) as a function of distance 'r' of the…

🧠 The Probability Peak Probability density ($\psi^2$) is the likelihood of finding an electron at a specific distance from the nucleus. For "s" orbitals, the electron is most likely to be found... right at the start ($r=0$).

🗺️ The 2s Profile

1. At the Nucleus: Unlike p or d orbitals, s-orbitals have maximum density at $r=0$. The graph starts at its peak.
2. The Node: A 2s orbital has $2 - 0 - 1 = 1$ radial node. The graph must touch the x-axis exactly once.
3. The Second Max: After the node, the wave function has a smaller "hump" before decaying to zero at infinity.
4. Conclusion: The graph must start high, cross zero once, and then have a second smaller peak. This is correctly shown in Option (b).

⚡ The "Touch and Go" Rule Wavelength density $\psi^2$ can never be negative. So the graph should never dip below the x-axis; it merely "kisses" it at the node.

⚠️ Common Traps Don't pick a graph that starts at zero! Only p, d, and f orbitals start at zero. All s-orbitals are "nuclear touchers."

$\boxed{\text{Answer: (b)}}$