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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: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.