By the addition of Ar gas to the system 2HI  H₂ + I₂, the degree of dissociation of HI will be -

Explanation:

Degree of dissociation:

• The phenomenon to generate current-carrying free ions or free radicals when a given concentration of solution components is taken infraction with the solute.
• The degree of dissociation is calculated by -

Degree of dissociation = 

Factors Affecting the Degree of dissociation:

• Dilution or change in concentration.
• Temperature.
• Nature of electrolyte.
• Nature of electrolyte.
• Nature of the solvent.

Calculation:

2HI  H2 + I₂

At t = 0, concentration is 1 mole

At t = t eq concentration

2HI  H2 + I2

HI is 1-2a,

the concentration of H₂ is "a" mole and the concentration of I₂ is "a" mole then,

The degree of dissociation of HI is given by K_c

Where, K_c = 

Kc = a × a / (1 - 2a)² = a² / (1-2a)²

Here, there will be no impact on the degree of dissociation constant due to the addition of Ar.