A4.0g sample of iron was heated from 0c to 20c. it absorbed 35.2j of energy as heat. what is the specific heat of this piece of iron

We are going to use the heat absorbed formula:

Q = M*C*ΔT

when Q is the heat absorbed = 35.2 J

and M is the mass of iron = 4 g 

and C is the specific heat capacity of iron (which we need to calculate)

ΔT the change in temperature = 20-0 = 20 °C

so, by substitution:

35.2 J = 4 g * C * 20°C

∴ the specific heat of this piece of iron C =  35.2 / (4g*20°C)

                                                                     = 0.44 J/g.°C