A human RBC is placed in 1.5% salt solution . It will :-

Options

A. swell up
B. shrink
C. remain unaffected
D. burst

Explanation

To solve the question of what happens to a human RBC when placed in a 1.5% salt solution, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Tonicity**:
- Tonicity refers to the relative concentration of solutes in a solution compared to the concentration of solutes inside a cell. It helps determine the direction of water movement across a semipermeable membrane.

2. **Identify the Isotonic Solution for Human RBCs**:
- The isotonic solution for human red blood cells (RBCs) is approximately 0.9% salt solution. In this solution, there is no net movement of water into or out of the cells, and they remain unchanged.

3. **Determine the Nature of the 1.5% Salt Solution**:
- The 1.5% salt solution has a higher concentration of salt compared to the isotonic 0.9% solution. Therefore, it is classified as a hypertonic solution.

4. **Predict Water Movement**:
- In a hypertonic solution, water moves from an area of lower solute concentration (inside the RBCs) to an area of higher solute concentration (the surrounding solution). This movement occurs in an attempt to equalize solute concentrations on both sides of the membrane.

5. **Conclude the Effect on RBCs**:
- As water exits the RBCs to balance the solute concentrations, the cells will lose water and consequently shrink. This process is known as crenation.

6. **Select the Correct Answer**:
- Based on the analysis, the correct answer to the question is that the RBCs will shrink when placed in a 1.5% salt solution.

### Final Answer:
The human RBC will **shrink** when placed in a 1.5% salt solution.

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