Answer
a) Mg b) H c) Si, d) Fe, e) F and Cl. Cl is the most abundant.
Work Step by Step
a) Main group metals in the chart: Li, Be, Na, Mg, Al, K, Ca.
From these the most abundant is Magnesium (Mg) with $10^8$ relative abundance.
b) Nonmetals in the chart: H, He, C, N, O, F, Ne, P, S, Cl, Ar.
From these the most abundant is Hydrogen (H) with $10^{12}$ relative abundance.
c) Metalloids in the chart: B, Si.
From these the most abundant is Silicon (Si) with $10^8$ relative abundance.
d) Transition metals in the chart: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn.
From these the most abundant is Iron (Fe) with $10^8$ relative abundance.
e) Halogens in the chart: F, Cl.
From these the most abundant is Chlorine (Cl) with $10^6$ relative abundance.
