The key to this problem lies in the value of the specific heat of iron.
This tells you that in order to increase the temperature of one unit of mass of iron, i.e. of #color(blue)("1 g")# of iron, by one unit of temperature, i.e. by #color(darkorange)(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
This tells you that in order to increase the temperature of #"35.0 g"# of iron by #color(darkorange)(1^@"C")#, you need to provide it with #"3.78 cal"# of heat. In your case, the temperature of the iron must increase by
which means that you will need
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
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