Two solutions with equal osmotic pressures are
**Core Concept**
The question is testing the concept of osmotic pressure and its relationship with solute concentration. Osmotic pressure is a colligative property that depends on the number of solute particles in a solution, not their size or type. This principle is crucial in understanding how different solutions interact with each other and with cells.
**Why the Correct Answer is Right**
When two solutions have equal osmotic pressures, it means that they have the same number of solute particles per unit volume. This is often achieved when the solutions have the same concentration of a non-permeable solute, such as sucrose or sodium chloride. The osmotic pressure of a solution is directly proportional to the concentration of the solute particles, so when the concentrations are equal, the osmotic pressures are also equal. In this case, the correct answer is a solution with equal concentrations of a non-permeable solute.
**Why Each Wrong Option is Incorrect**
* **Option A:** A solution with a higher concentration of a non-permeable solute would have a higher osmotic pressure than the other solution, making it incorrect.
* **Option B:** A solution with a lower concentration of a non-permeable solute would have a lower osmotic pressure than the other solution, making it incorrect.
* **Option C:** A solution with a different type of solute, such as glucose, would not necessarily have the same osmotic pressure as the other solution, even if they have the same concentration. This is because different solutes have different permeability coefficients, making it incorrect.
**Clinical Pearl / High-Yield Fact**
When comparing two solutions with equal osmotic pressures, it's essential to consider the type and concentration of the solute particles. Remember, the osmotic pressure of a solution is a colligative property that depends on the number of solute particles, not their size or type.
**Correct Answer:** D. A solution with equal concentrations of a non-permeable solute.