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9

Explanation:

n-factor of NaOH = 1

OH⁻ concentration = Normality of NaOH

                             = Molarity x n-factor

                             = 10⁻⁵ x 1

                             = 10⁻⁵  

Now, pOH = -㏒(OH⁻)

        pOH = -㏒(10⁻⁵)

        pOH = 5

We know pH + pOH = 14

               pH = 14 - 5 = 9

∴pH of 10⁻⁵M NaOH is 9

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.