Mass of the substance (m) = 18.3 g
Initial temperature T1 = 25 C
Final temperature T2 = 45 C
Heat absorbed by the substance (Q) = 1.647*10^2 J
Specific heat = c
Formula:
Q = m*c*ΔT
= m*c*(T2-T1)
c = Q/m*(T2-T1) = 1,647*10^2 J/18.3 g *(45-25)C
c = 0.45 J/g C
The substance with a specific heat capacity of 0.45 J/g C is iron.