The subshell notation is derived from the principal quantum number ($n$) and the azimuthal quantum number ($l$). The value of $l$ corresponds to specific subshells: $l=0 \rightarrow s$, $l=1 \rightarrow p$, $l=2 \rightarrow d$, $l=3 \rightarrow f$ , .

1. For (a) $n = 2, l = 1$: The shell is 2 and the subshell is p ($l=1$). Representation: 2p. Matches (iii).
2. For (b) $n = 3, l = 2$: The shell is 3 and the subshell is d ($l=2$). Representation: 3d. Matches (iv).
3. For (c) $n = 3, l = 0$: The shell is 3 and the subshell is s ($l=0$). Representation: 3s. Matches (ii).
4. For (d) $n = 2, l = 0$: The shell is 2 and the subshell is s ($l=0$). Representation: 2s. Matches (i).

Correct matching sequence: (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i).