For Hot water:
Mass=80g
S.H.C=4.2Jg−1oC−1
InitialTemp.=60oC
FinalTemp.=30oC=θF=(60−30)=30oC
for Cold water:
Mass=100g
S.H.C=4.2Jg−1oC−1
InitialTemp.=20oC
FinalTemp.=30oC
=θR=(30−20)
=10oC
for Vessel:
Mass=?(m)
S.H.C=?(c)
InitialTemp.=20oC
Letthermalcapacityofvessel=x=mc
Heatlostbyhotwater=mcθF
=80×4.2×30
=10080J
Heatgainedbycoldwater=mcθR
=100×4.2×10
=4200J
Heatgainedbyvessel=mcθR
=x×10oC
Heatgained=Heatlost
4200+(x×10)=10080J
x=(10080−4200)10JoC−1
=588JoC−1