We are given that it takes 7 joules of heat to raise the temperature of the bar by 1°C. Therefore this means that the heating capacity Cp is:
Cp = 7 J / °C
The formula for the amount of heat required is:
heat = Cp (Tf – Ti)
where Ti is initial temperature = 25°C, and Tf is the final temperature
When Tf = 26°C
heat = 7 (26 – 25) = 7 J
When Tf = 27°C
heat = 7 (27 – 25) = 14 J
When Tf = 28°C
heat = 7 (28 – 25) = 21 J
When Tf = 29°C
heat = 7 (29 – 25) = 28 J
When Tf = 30°C
heat = 7 (30 – 25) = 35 J
When Tf = 35°C
heat = 7 (35 – 25) = 70 J
