The correct option is B 454.04Jkg−1K−1
Mass of iron, M=0.05kg
Initial temperature of iron, t1=200oC
Final temperature of iron, t2=22.4oC
Mass of water, m=0.4kg
Initial temperature of water, t3=20oC
Final temperature of water, t2=22.4oC
Specific heat capacity of water
=4200Jkg−1K−1
Let specific heat capacity of iron =C
Heat lose by iron =MC(t1−t2)
=0.05×C×(200−22.4)
=0.05×C×177.6=8.88CJ
Heat gained by water
=m×4200×(t2−t3)
=0.4×4200×(22.4−20)
=0.4×4200×2.4=4032J
Equating heat lost and heat gained
8.88C=4032
Therefore, C=4032/8.88
=454.04Jkg−1K−1.