Question

For hydrogen atom, the orbitals with the lowest energy among the given orbitals are: (i) $4s$ (ii) $2p_x$ (iii) $3d_{z^2}$ (iv) $2p_y$

• A. (i) & (iii)
• B. (ii) & (iv)
• C. (ii) & (iii)
• D. (ii) only
• E. (i) only

Hint:

For H-atoms, energy levels are $1s < 2s = 2p < 3s = 3p = 3d$.

Answer 1

The Correct Option is B

Step 1: Concept
In a hydrogen atom, energy depends only on the principal quantum number $n$.

Step 2: Meaning
Orbitals with the same $n$ value have the same energy (degenerate).

Step 3: Analysis
$2p_{x}$ and $2p_{y}$ both have $n=2$, which is lower than $n=3$ or $n=4$.

Step 4: Conclusion
Orbitals (ii) and (iv) have the lowest energy. Final Answer: (B)