A 0.4 m × 0.4 m square plate at 400 K is suspended vertically in still air at 300 K; ν = 20.75 × 10^{−6} m^{2}/s, Pr = 0.697, k = 0.03 W/m·K, β = 2.86 × 10^{−3} K^{−1}. Find (i) Gr (dimensionless), (ii) the average h (answer in W/m^{2}·K), with Nu = 0.518(Gr·Pr)^{1/4}.