Calculate the hydrogen ion concentration in the following biological fluids whose `pH` are given below:
a. Human muscle-fluid, `6.83`
b. Human stomach fluid, `1.2`
c. Human blood, `7.38`
d. Human saliva, `6.4`.

Explanation

To calculate the hydrogen ion concentration \([H^+]\) from the given pH values of various biological fluids, we will use the formula:

\[ [H^+] = 10^{-\text{pH}} \]

Let's solve for each case step by step:

### a. Human Muscle Fluid, pH = 6.83

1. **Identify the pH value**: The pH of human muscle fluid is 6.83.
2. **Apply the formula**:
\[ [H^+] = 10^{-6.83} \]
3. **Calculate**:
\[ [H^+] \approx 1.479 \times 10^{-7} \, \text{M} \]

### b. Human Stomach Fluid, pH = 1.2

1. **Identify the pH value**: The pH of human stomach fluid is 1.2.
2. **Apply the formula**:
\[ [H^+] = 10^{-1.2} \]
3. **Calculate**:
\[ [H^+] \approx 6.31 \times 10^{-2} \, \text{M} \]

### c. Human Blood, pH = 7.38

1. **Identify the pH value**: The pH of human blood is 7.38.
2. **Apply the formula**:
\[ [H^+] = 10^{-7.38} \]
3. **Calculate**:
\[ [H^+] \approx 4.17 \times 10^{-8} \, \text{M} \]

### d. Human Saliva, pH = 6.4

1. **Identify the pH value**: The pH of human saliva is 6.4.
2. **Apply the formula**:
\[ [H^+] = 10^{-6.4} \]
3. **Calculate**:
\[ [H^+] \approx 3.98 \times 10^{-7} \, \text{M} \]

### Summary of Results:
- a. Human Muscle Fluid: \([H^+] \approx 1.479 \times 10^{-7} \, \text{M}\)
- b. Human Stomach Fluid: \([H^+] \approx 6.31 \times 10^{-2} \, \text{M}\)
- c. Human Blood: \([H^+] \approx 4.17 \times 10^{-8} \, \text{M}\)
- d. Human Saliva: \([H^+] \approx 3.98 \times 10^{-7} \, \text{M}\)