What is the typical size range of particles in a colloidal solution?

RRB Nsg. Superintendent-2026 (Shift -2nd)

Biochemistry and Nutrition

Easy

Appeared in: RRB Nsg. Superintendent-2026 (Shift -2nd)

Explanation

Colloidal solutions contain dispersed particles that are intermediate in size, falling between those of a true solution and a suspension.
The scientifically accepted size range for colloidal particles is from 1 to 1000 nanometers (nm).
The option '1 to 100 nanometers' fits perfectly within this classification and represents the core range for many nanoscale applications in medicine.
Unlike true solutions, colloids are large enough to scatter light (Tyndall effect), and unlike suspensions, they are small enough to resist settling due to gravity.

Option B: This describes macroscopic particles. A size of 1 millimeter is equal to 1,000,000 nanometers, which is far too large for a colloid and would be considered a very coarse suspension.
Option C: This particle size range (greater than 1000 nm) is the defining characteristic of a suspension, not a colloid. Particles of this size are visible and will settle out from the medium.
Option D: This particle size is characteristic of a true solution, where solute particles are individual atoms, ions, or small molecules completely dissolved in the solvent.

Visual 1: Diagram: Comparison of True Solution, Colloidal Solution, and Suspension. This visual should illustrate the relative particle sizes and show a light beam passing through each. The beam should be invisible in the true solution, visible in the colloid (Tyndall effect), and blocked/scattered by large particles in the suspension.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of mixtures based on particle size as background academic context rather than a clinical decision trigger.
Many biological fluids are colloids. Blood plasma is a prime example, where proteins like albumin (colloidal particles) maintain colloid osmotic pressure, which is vital for regulating fluid balance between blood vessels and tissues.
In clinical practice, intravenous (IV) colloid solutions (e.g., albumin, dextran, hetastarch) are used as plasma volume expanders to treat conditions like hypovolemic shock by increasing the osmotic pressure within blood vessels.
The principles of nanotechnology, which operates in the 1-100 nm range, are being applied in nanomedicine to create nanoparticles for targeted drug delivery, diagnostics, and imaging.

How to Approach the Question

This is a factual recall question based on a fundamental concept in chemistry.
Identify the key term in the question: 'colloidal solution'.
Recall the three main types of mixtures classified by particle size: true solutions, colloids, and suspensions.
Remember the approximate size ranges for each category: solutions (<1 nm), colloids (1-1000 nm), and suspensions (>1000 nm).
Evaluate each option against these established ranges.
Select the option that falls within the defined range for a colloid. '1 to 100 nanometers' is the only choice that fits this criterion.

Concept Tested & Keywords

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