How does a buffer resist change in pH upon addition of a strong acid?
Concepts and reason
Buffer solution is a solution which maintains its pH value on addition of small amount of strong acid or strong base into it. It is a solution which resists the change in pH.
Fundamentals
Acidic buffer solutions are the solutions which have a pH less than 7. These solutions are made from weak acid and one of its salts.
Basic buffer solutions are the solutions which have a pH greater than 7. These solutions are made from weak base and one of its salts.
Answer:
When a strong acid is added to buffer solution then conjugate base present in buffer solution takes its hydronium ion converting it into weak acid of conjugate base and water.
Due to this, amount of weak acid increases and amount of conjugate base decreases.
Explanation:
When a strong acid is added to the buffer solution then it reacts with weak base in the buffer to form a weak acid.
By adding strong acid in buffer solution, amount of weak acid increases. There will be a little change in pH.
Explanation:
Amount of weak acid is increased by adding strong acid in the buffer solution. Since the acid is weak. So, it produces only a few 
ions in the buffer solution and pH of the buffer decreases by very small amount.