Which is not true regarding the ph scale?

the neutral ph at 25°c is 7.0.

bases have a ph greater than 7.0.

the ph scale measures the hydronium ion concentration in solution.

when the concentration of hydroxide ions increases, the ph decreases.

When the concentration of hydroxide ions increases, the pH decreases.

Explanation: pH or pOH is the measure of acidity or alkalinity.  

pH is defined as negative logarithm of hydrogen ion concentration. pOH is defined as the negative logarithm of hydroxide ion concentration.

Acids have pH ranging from 1 to 6.9, neutral solutions have pH of 7 and bases have pH ranging from 7.1 to 14.

Thus as pOH and are inversely related, a solution having high concentration of will have low pOH and thus high pH.

there is none because earth is stationary and flat.