Which solution is isotonic to the blood ?

Options

A. 0.75% by weight of NaCl approximately
B. 0.99% by weight of NaCl approximately
C. 0.90% by weight of NaCl approximately
D. None of these

Answer

To determine which solution is isotonic to blood, we need to understand the concept of isotonic solutions and the osmotic pressure associated with them.

### Step-by-Step Solution:

1. **Understand Isotonic Solutions**:
- Isotonic solutions have the same osmotic pressure. This means that when two solutions are separated by a semipermeable membrane, there will be no net movement of water between them.

2. **Identify Normal Saline**:
- Normal saline is a commonly used isotonic solution in medical settings. It is defined as a solution of 0.9% NaCl (sodium chloride) by weight.

3. **Review the Options**:
- The options given are:
- A) 0.75% NaCl
- B) 0.99% NaCl
- C) 0.9% NaCl
- D) An Abyss (not a valid option)

4. **Compare with Normal Saline**:
- Since normal saline is 0.9% NaCl, we can compare the options:
- A) 0.75% NaCl is hypotonic (lower osmotic pressure).
- B) 0.99% NaCl is slightly hypertonic (higher osmotic pressure).
- C) 0.9% NaCl is isotonic (same osmotic pressure).
- D) An Abyss is not a valid solution.

5. **Conclusion**:
- The solution that is isotonic to blood is **0.9% NaCl**.

### Final Answer:
- The correct answer is **C) 0.9% NaCl**.