How much heat would be needed to raise the temperature of 25.0 g of water by 18#"^@#C?
The specific heat of water is 4.18 J/(g·°C).
This means that it takes 4.18 J to raise one gram of water one degree.
Multiply that by 25.0 g and 18°C.
The units cancel out and you get joules.
18 °C has 2 sig figs, so you give your answer to 2 sig figs.