The ion product of water: varies with pH
remains constant regardless of the pH
ranges between 1.0 and 10 -14
is only applicable to neutral water

remains constant regardless of the pH

Explanation:

The pH refers to the hydrogen potential or hydrogen power that states the aqueous solution acidity. It varies from 0 to 14. The higher pH values denotes  more basic solutions while on the other hand,  the lower pH values denote more acidic

An acidic solution refers to a solution at which the hydrogen ions concentration is more than the hydroxide ions concentration

Therefore the ion product of water remains constant as the value of both hydrogen ions and hydroxide ions is relatively small as non-dissociated water concentration would remain the same.

Hence, the second option is correct

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.