Final answer:
Hypoventilation decreases blood pH and can lead to acidosis, whereas hyperventilation can result in a higher pH, causing alkalosis.
Step-by-step explanation:
The condition that decreases blood pH leading to alkalosis is hypoventilation, not hyperventilation. Hypoventilation reduces the exhalation of carbon dioxide, consequently increasing blood carbon dioxide levels which results in a lower pH, meaning the blood becomes more acidic. On the contrary, hyperventilation causes one to exhale more carbon dioxide than normal, which leads to low blood carbon dioxide levels and a higher pH, indicating a more alkaline (or basic) condition, which is known as respiratory alkalosis.
Therefore, when the ventilation rate is decreased, carbon dioxide levels rise, leading to increased acidity in the blood. This is the opposite effect of hyperventilation, which can occur during panic attacks or asthma and is characterized by an excessively fast breathing rate that expels too much carbon dioxide, thereby elevating the blood's pH.