Question

Fear or excitement generally causes one to breathe rapidly and it results in the decrease of concentration of ${CO}_2$ in blood. In what way, it will change the $pH$ of blood?

• A. $pH$ will increase
• B. $pH$ will decrease
• C. No change
• D. $pH$ will be $7$

Answer 1

Answer: (C)

No change

As we know, $C{O}_2$ is acidic in nature. So, a decrease in its concentration should increase the $pH$. But, blood contains serum which has proteins in it. This acts as a buffer solution. We already know that buffer solutions resist a change in the $pH$ even on addition of a small amount of acid or small amount of base or dilution, etc.

Therefore, the $pH$ of the blood remains unaffected.

Hence,option C is correct.