hope it helps youExplanation:The KEY to this problem lies in the value of the specific heat of IRON. c iron = 0.108 cal  g − 1 ∘ C − 1 This TELLS you that in order to increase the temperature of one UNIT of mass of iron, i.e. of  1 g of iron, by one unit of temperature, i.e. by  1 ∘ C , you NEED to provide it with  0.108 cal . Now, you can use the specific heat of iron to figure out the amount of heat needed to increase the temperature of  35.0 g of iron 35.0 g ⋅ 0.108 cal 1 g ⋅ 1 ∘ C = 3.78 cal  ∘ C − 1 This tells you that in order to increase the temperature of  35.0 g of iron by  1 ∘ C , you need to provide it with  3.78 cal of heat. In your case, the temperature of the iron must increase by 35 ∘ C − 25 ∘ C = 10 ∘ C which means that you will need 10 ∘ C ⋅ 3.78 cal 1 ∘ C = 37.8 cal Now, you should round the answer to one significant figure, the number of sig figs you have for the change in temperature, i.e. for  10 ∘ C , but I'll leave it rounded to two sig figs heat needed = 38 cal −−−−−−−−−−−−−−−−−−