A certain orbital has no angular nodes and two radial nodes. The orbital is :

Solution

Chemistry ma’am · 4 steps

Angular nodes give you l, then radial nodes give you n. Read l first, then n.

1. Two node formulas. An orbital has l angular nodes and n - l - 1 radial nodes. Together they make n - 1 nodes in all.
2. Find l. No angular nodes means l = 0, so this is an s orbital. That already rules out 2p and 3p.
3. Find n. Two radial nodes means n - 0 - 1 = 2, so n = 3.

   Orbital	Angular nodes (l)	Radial nodes (n - l - 1)
   2s	0	2 - 0 - 1 = 1
   3s	0	3 - 0 - 1 = 2
   3p	1	3 - 1 - 1 = 1
   2p	1	2 - 1 - 1 = 0

4. So. With n = 3 and l = 0, the orbital is 3s, which is option (b).

The idea to keep. Angular nodes equal l. Radial nodes equal n - l - 1. Get l from the angular count first, then use the radial count to find n.

Answer from the NTA final answer key. Solution by PrepWiser.