Question

in a liter of pure water, the addition of a 0.01 m strong acid results in a ph change from 7 to 2. however, if the same amount of acid is added to blood, the ph changes from 7.4 to 7.3. why does blood respond differently than water to the acid?
the blood is highly alkaline in nature and neutralizes the acid.
the blood neutralizes the acid by taking in extra water.
the density of the blood resists any change in its ph.
the buffers present in the blood resist the ph change.

Explanation:

Blood contains buffer systems (like bicarbonate buffer) that can neutralize added acid or base, minimizing pH change. Pure water lacks such buffers, so adding acid causes a large pH drop. The other options are incorrect: blood isn't highly alkaline to neutralize acid (its pH is ~7.4, slightly alkaline), blood doesn't neutralize acid by taking extra water, and density has no role in pH resistance.

Answer:

The buffers present in the blood resist the pH change.