Question

which of the following ratio is constant for an isolated conductor

Answer 1

An isolated conductor is the type of conductor in which an electric field is zero everywhere and any excess charge resides entirely on it's surface. 

The charge-to-potential ratio of an isolated conductor is constant and is known as capacitance. It is written as,
C = Q / Ф
Where, C is the capacitance, Q is the charge and Ф is the potential of an isolated conductor. The units of capacitance are farads (F) or coulomb's per volt (CV⁻¹).

Answer 2

The Charge To Potential Ratio Is Constant For An Isolated Conductor

Total Charge/Potential = Isolated