Conversion factor for converting partial pressures (in Kp) to active masses (in Kc) is given by option (b) 1/RT.

Explanation:
To understand the conversion factor for converting partial pressures (in Kp) to active masses (in Kc), let's first understand the concepts of partial pressure and active mass.

Partial Pressure (Kp):
Partial pressure is the pressure exerted by a component of a mixture of gases. It is defined as the pressure that the gas would exert if it occupied the same volume alone at the same temperature. The partial pressure of a gas is directly proportional to its mole fraction in the mixture.

Active Mass (Kc):
Active mass is the concentration of a substance in terms of its molar quantities in a chemical reaction. It is defined as the ratio of the number of moles of a substance to the volume in which it is present. Active mass is used to express the concentration of reactants and products in terms of moles per unit volume.

Conversion Factor:
To convert partial pressures (in Kp) to active masses (in Kc), we need a conversion factor that relates the two quantities. This conversion factor is derived from the ideal gas equation.

The ideal gas equation is given by:
PV = nRT

Where:
P = Pressure
V = Volume
n = Number of moles
R = Gas constant
T = Temperature

To convert partial pressures (in Kp) to active masses (in Kc), we need to consider the relationship between the partial pressure and the active mass in terms of moles. According to the ideal gas equation, the number of moles (n) can be expressed as:

n = PV/RT

From this equation, we can determine the conversion factor for converting partial pressures (in Kp) to active masses (in Kc). Dividing both sides of the equation by V, we get:

n/V = P/RT

Since the concentration of a substance is expressed as moles per unit volume, the left side of the equation represents the active mass (Kc), and the right side of the equation represents the partial pressure (Kp).

Therefore, the conversion factor for converting partial pressures (in Kp) to active masses (in Kc) is:

Kc = Kp/RT

To convert Kp to Kc, we need to divide the partial pressure (Kp) by the gas constant (R) multiplied by the temperature (T).

Hence, the correct answer is option (b) 1/RT.