Fear or excitement, generally cause one to breathe rapidly and it results in the decrease of concent — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

Blood relies on a carbonic acid-bicarbonate buffer system. Rapid breathing (hyperventilation) expels $\text{CO}_2$ from the lungs at a faster rate, lowering the concentration of dissolved $\text{CO}_2$ (and thus $\text{H}_2\text{CO}_3$) in the blood. According to the Henderson-Hasselbalch equation ($pH = pK_a + \log([\text{HCO}_3^-]/[\text{H}_2\text{CO}_3])$), a decrease in the denominator $[\text{H}_2\text{CO}_3]$ increases the ratio, thereby causing an increase in the blood pH (respiratory alkalosis). Therefore, correct answer is A.