We know that: Q=mL,Q=msΔθ
Given: m1=2 g, θ1=100∘C, m2=5 g, θ2=−40∘C, Lv=500 cal/g, sice=0.5 cal/g∘C, sw=1 cal/g∘C, Lf=80 cal/g
Heat given by steam in converting into water is
Q1=m1Lv
=2×500
=1000 cal …(i)
Heat taken by ice to convert to water at 100∘C fully is
Q2=m2sice(0−(−40))+m2Lf+m2sw(100−0)
Q2=(5×40×0.5)+(5×80)+(5×100×1)
Q2=1000 cal
As Q1=Q2
So, steam and water both are at 100∘C.
Final answer: 100∘C.