Question

Why is water more sensitive to the addition of HCl than the buffer solution?

Answer 1

What do you mean "the buffer solution"

Answer 2

Buffer solutions have the property to neutralise any changes by addition of small amount of acid or base. And that small amount differs from buffer to buffer. So after addition of HCl buffer neutralises effect of H+ and Cl- by using its own counter ions. But water has no such property. So water is more affected.

Answer 3

thank you @Rayan007