The given mass of water is,
[tex]m=1\text{ kg}[/tex]The value of the raise in the temperature is,
[tex]\Delta T=5^cC[/tex]The value of the specific heat of the water is,
[tex]c=4200\text{ }Jkg^{-1}C^{-1}[/tex]Thus, the energy needed to increase the temperature of water is,
[tex]\begin{gathered} Q=mc\Delta T \\ Q=1\times4200\times5 \\ Q=21000\text{ J} \\ Q=21\times10^3\text{ J} \\ Q=21\text{ kJ} \end{gathered}[/tex]Hence, the amount of energy required to raise the temperature of the water to 5 degree C is 21 kJ.
