Which of the following statements is true for displacement reactions?

RRB Nsg. Superintendent - 29 April 2025 (Shift-3rd)

General Knowledge

Easy

Appeared in: RRB Nsg. Superintendent - 29 April 2025 (Shift-3rd)

Explanation

A displacement reaction is defined by a more reactive element taking the place of a less reactive element in a compound.
This principle is governed by the reactivity series, which ranks elements based on their tendency to undergo chemical reactions.
An element higher in the series has a greater ability to form stable compounds, thus it can displace an element lower in the series.
For example, zinc is more reactive than copper, so it will displace copper from a copper sulfate solution.

Option A: This statement is the opposite of the definition of a displacement reaction. A less reactive element cannot displace a more reactive one because the compound formed by the more reactive element is more stable.
Option C: This is an incorrect generalization. Many displacement reactions are spontaneous and exothermic, occurring at room temperature without the need for heat.
Option D: This statement is false. Displacement reactions occur in both metals and non-metals. For example, iron (a metal) can displace copper, and chlorine (a non-metal) can displace bromine.

Visual 1: Diagram - The reactivity series of metals. This chart would visually rank common metals (like Potassium, Sodium, Calcium, Magnesium, Aluminium, Zinc, Iron, Lead, Copper, Silver, Gold) from most reactive to least reactive, helping to predict the outcome of displacement reactions.
Visual 2: Illustration - A beaker containing a blue copper sulfate solution with a piece of zinc metal in it. An arrow would show the blue color fading and a reddish-brown deposit of copper forming on the zinc, illustrating the reaction Zn + CuSO₄ → ZnSO₄ + Cu.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Definition and characteristics of displacement reactions as background academic context rather than a clinical decision trigger.
While a concept from general chemistry, the principle of displacement has parallels in pharmacology. For instance, drug displacement from plasma protein binding sites can occur when a drug with a higher affinity for the protein displaces another drug with a lower affinity.
This can increase the free (unbound) concentration of the displaced drug, potentially leading to toxicity. An example is salicylates displacing warfarin from albumin, increasing the anticoagulant effect and risk of bleeding.
What if? If a patient on a stable dose of warfarin (which is highly protein-bound) starts taking high doses of aspirin (a salicylate), the nurse must monitor for signs of increased bleeding (e.g., bruising, hematuria) because the aspirin can displace warfarin, increasing its free concentration and therapeutic effect to a dangerous level.

How to Approach the Question

First, identify the core concept of the question, which is 'displacement reactions'.
Recall the fundamental definition of a displacement reaction. This type of reaction involves one element replacing another in a compound.
Remember the key rule governing these reactions: reactivity. A more reactive element will displace a less reactive element.
Evaluate each option against this fundamental rule.
Option B directly matches the definition: 'A more reactive element replaces a less reactive one.'
Check the other options to confirm they are incorrect. Option A is the opposite. Option C is a false generalization (not all require heat). Option D is also a false generalization (they occur with metals too).

Concept Tested & Keywords

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