Statement - I. Blood cells are isotonic with 0.16 M NaCl solution.
Statement - II. Cell wall of blood cells acts as semi-permeable membrane.

Options

A. Statement-1 is true, statement-2 is true and statement-2 is correct explanation for statement-1.
B. Statement-1 is true, statement-2 is true and statement-2 is NOT the correct explanation for statement-1.
C. Statement-1 is true, statement-2 is false.
D. Statement-1 is false, statement-2 is true.

Answer

To analyze the statements provided in the question, we will evaluate each statement step by step.

### Step 1: Evaluate Statement I
**Statement I:** Blood cells are isotonic with 0.16 M NaCl solution.

1. **Understanding Isotonic Solutions:**
- Two solutions are considered isotonic when they have the same osmotic pressure. This means that the concentration of solutes in both solutions is equal, and there will be no net movement of water across a semi-permeable membrane separating them.

2. **Osmotic Pressure Calculation:**
- The formula for osmotic pressure (π) is given by:
\[ \pi = i \cdot C \cdot R \cdot T \]
- Where:
- \(i\) = van 't Hoff factor (number of particles the solute dissociates into)
- \(C\) = molarity of the solution
- \(R\) = universal gas constant (0.0821 L·atm/(K·mol))
- \(T\) = temperature in Kelvin

3. **Calculating for NaCl:**
- For NaCl, it dissociates into two ions: Na⁺ and Cl⁻, so \(i = 2\).
- Given \(C = 0.16\) M and assuming \(T = 27°C = 300 K\) (273 + 27):
\[ \pi = 2 \cdot 0.16 \cdot 0.0821 \cdot 300 \]
- Performing the calculation:
\[ \pi = 2 \cdot 0.16 \cdot 0.0821 \cdot 300 \approx 7.872 \text{ bar} \]
- The osmotic pressure of blood cells is approximately 7.8 bar, which is similar to the calculated osmotic pressure of the 0.16 M NaCl solution.

4. **Conclusion for Statement I:**
- Since the osmotic pressures are approximately equal, **Statement I is true**.

### Step 2: Evaluate Statement II
**Statement II:** Cell wall of blood cells acts as a semi-permeable membrane.

1. **Understanding Semi-permeable Membranes:**
- A semi-permeable membrane allows certain molecules or ions to pass through it while blocking others. Typically, it allows the passage of solvent molecules (like water) but restricts solute molecules.

2. **Blood Cell Membrane Functionality:**
- The cell membrane of blood cells (specifically red blood cells) is indeed semi-permeable. It allows water to move in and out of the cell while preventing larger solute molecules from passing freely.

3. **Conclusion for Statement II:**
- Since the blood cell membrane does allow the movement of solvent (water) while restricting solute movement, **Statement II is true**.

### Step 3: Determine Relationship Between Statements
- Both statements are true, but we need to check if Statement II provides a correct explanation for Statement I.
- While both statements are true, the fact that blood cells are isotonic with a NaCl solution does not depend on the semi-permeable nature of the cell wall. The isotonic condition is based on osmotic pressure equivalence.

### Final Conclusion:
- **Statement I is true.**
- **Statement II is true.**
- **Statement II is not the correct explanation for Statement I.**

Thus, the answer is: **Both statements are true, but Statement II is not the correct explanation of Statement I.**

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