Which of the following has highest pH?

Options

A. Human saliva
B. Human blood
C. Gastric juice
D. Urine

Answer

To determine which of the following has the highest pH, we will analyze the pH levels of each option provided:

1. **Human Saliva**: The pH of human saliva is slightly acidic, approximately **6.8**.
2. **Human Blood**: The pH of human blood is alkaline, measuring around **7.4**.
3. **Gastric Juice**: Gastric juice is highly acidic due to the presence of hydrochloric acid (HCl), with a pH ranging from **1 to 2** (commonly around **1.8**).
4. **Urine**: The pH of urine is also acidic, generally around **6**.

Now, let's compare these pH values:

- Human Saliva: **6.8**
- Human Blood: **7.4**
- Gastric Juice: **1.8**
- Urine: **6**

From this comparison, we can see that the pH of human blood (7.4) is the highest among the options given.

**Conclusion**: The substance with the highest pH is **human blood**.