If we place the cells in a solution containing more than 0.9% (mass/volume) sodium chloride, which of the following observation is true?

All of these

The correct answer is option 4. All of these.

If we place cells in a solution containing more than 0.9% (mass/volume) sodium chloride, the following observation is true: all of these

When the cells are placed in a solution with a higher concentration of sodium chloride (more than 0.9%), which is hypertonic compared to the cells' cytoplasm, the following will occur:

1. Water will flow out of the cells: Due to the higher concentration of solute (sodium chloride) outside the cells, water will move out of the cells by osmosis, trying to equalize the concentration on both sides of the cell membrane.

2. Solution is hypertonic: The solution with more than 0.9% sodium chloride is hypertonic compared to the cells. "Hypertonic" means it has a higher solute concentration than the cytoplasm of the cells.

3. Cells would shrink: As water moves out of the cells, they would lose volume and shrink. This is known as plasmolysis, where the cytoplasm of the cell contracts away from the cell wall.

These observations are a result of the osmotic movement of water across the semi-permeable cell membrane in response to the difference in solute concentration between the solution and the cells.