What is the pH of the buffer system after the addition of 0.10 mole of gaseous HCl to 1 L of the solution

You didn't provide information about the buffer system.

To determine the pH of the buffer system after the addition of gaseous HCl, we'll need some additional information about the buffer solution.

A buffer solution is a mixture of a weak acid and its conjugate base (or a weak base and its conjugate acid). It resists changes in pH when a small amount of an acid or base is added to it.

The pH of a buffer solution can be calculated using the Henderson-Hasselbalch equation, which is given by:

pH = pKa + log([A-]/[HA])

Where:
pH is the hydrogen ion concentration in the solution
pKa is the negative logarithm of the acid dissociation constant of the weak acid
[A-] is the concentration of the conjugate base
[HA] is the concentration of the weak acid

To solve this problem, we need to know the initial concentrations of the weak acid and its conjugate base in the buffer solution. Without this information, it's not possible to calculate the pH accurately.

If you have the initial concentrations of the weak acid and conjugate base, please provide them, and I'll be happy to help you calculate the pH of the buffer solution after the addition of gaseous HCl.