We know that the pH meter (concentration cell-based potentiometric measurement of hydronium ions) responds to activity rather than concentration because the response is linear at 59.2 mV/decade over 10 orders of magnitude (from pH 2 to 12). If it was responding to concentration, how much different would the response be to pure water than to 1.0 M NaCl? And what should happen to the slope of the curve going up and down in concentration of hydronium [H3O+] by a factor of ten from pure water (assume the source of the change is HCl in one direction and NaOH in the other and that there is no other contributor to the ionic strength