A glass flask is filled up to a mark with 50 cc of mercury at 18°C. If the flask and contents are heated to 38°C, how much mercury will be above the mark ? (α for glass is  9 x 10-6/°C and coefficient of real expansion of mercury is 18 x 10-3/°C)

Volume of mercury at 18°C = V0 = 50 ccVolume of mercury at 38°C = (V38)r                   =V01+γm⋅ΔtVolume of flask at 38∘C=V38f             =V01+γfΔt∴Volume of mercury at 38°C above the mark            =V01+γmΔt−V01+γfΔt=V0γm−γfΔt=5018×10−3−3×9×10−6(38−18)=0⋅153 cc