$(a)$ In this ladder (Figure),symbols of elements are jumbled up. Rearrange these symbols of elements in the increasing order of their atomic number in the Periodic Table.
$(b)$ Arrange them in the order of their group also.

(N/A) The elements present in the ladder are: $H, He, Li, Be, B, C, N, O, F, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca$.
Arranging them in increasing order of their atomic number $(Z)$:
$H (1), He (2), Li (3), Be (4), B (5), C (6), N (7), O (8), F (9), Ne (10), Na (11), Mg (12), Al (13), Si (14), P (15), S (16), Cl (17), Ar (18), K (19), Ca (20)$.
$(b)$ Arranging them according to their groups:
Group $1: H, Li, Na, K$
Group $2: Be, Mg, Ca$
Group $13: B, Al$
Group $14: C, Si$
Group $15: N, P$
Group $16: O, S$
Group $17: F, Cl$
Group $18: He, Ne, Ar$