JEE Main · 2022 · 27 Jun 2022 · Shift 2 · Atomic Structure

A set of quantum numbers is allowed only when the principal number $n$ is a positive integer, the azimuthal number obeys $0\le l\le n-1$, and the magnetic number lies in the range $-l\le m_l\le +l$. Testing the rows in turn: for A, $n=3$ paired with $l=3$ is impossible because $l$ can reach only $n-1=2$; for B, $n=3,l=2,m_l=-2$ satisfies every condition and is valid; for C, $n=2,l=1,m_l=+1$ is likewise valid; and for D, $n=2$ with $l=2$ again breaks $l\le n-1=1$. Only the sets B and C survive, so the number of correct sets is $2$.