Answer:
20°C
Explanation:
Quantity if heat energy supplied is expressed as;
Q = mcΔt
m is the mass = 3kg
Δt is the temperature rise
Q = 5400J
c = 900 J/kg °C
Substitute
5400 = 3(90)Δt
5400 = 270Δt
Δt = 5400/270
Δt = 20°C
Hence the temperature rise is 20°C