[tex]\bull\sf m=0.47kg[/tex]
[tex]\bull\sf \Delta T=T_f-T_i=48.4-30.5=17.9°C[/tex]
[tex]\bull\sf Q=1.65\times 10^4J[/tex]
We know according to thermodynamics
[tex]\\ \sf\longmapsto Q=mc\Delta T[/tex]
[tex]\\ \sf\longmapsto c=\dfrac{Q}{m\Delta T}[/tex]
[tex]\\ \sf\longmapsto c=\dfrac{1.65\times 10^4}{0.47\times 17.9}[/tex]
[tex]\\ \sf\longmapsto c=\dfrac{1.65\times 10^4}{8.413}[/tex]
[tex]\\ \sf\longmapsto c=0.1961\times 10^4J/kg°C[/tex]
[tex]\\ \sf\longmapsto c=1961J/kg°C[/tex]