Which combination will result in a salt and water only?

RRB Nsg. Superintendent-2026 (Shift -3rd)

Biochemistry & Nutrition

Medium

Appeared in: RRB Nsg. Superintendent-2026 (Shift -3rd)

Explanation

The reaction between sulfuric acid (H₂SO₄), a strong acid, and potassium hydroxide (KOH), a strong base, is a classic neutralization reaction.
The products of this reaction are potassium sulfate (K₂SO₄), which is a salt, and water (H₂O).
The balanced chemical equation is H₂SO₄ + 2KOH → K₂SO₄ + 2H₂O.
This reaction is the only one among the options that produces only a salt and water, with no other byproducts like gases.

Option A: Nitric acid is an acid and carbon dioxide is an acidic oxide. Two acidic substances will not neutralize each other to form a salt and water.
Option C: The reaction between hydrochloric acid (an acid) and calcium carbonate (a base) produces a salt (calcium chloride) and water, but it also produces carbon dioxide (CO₂) gas. The question specifies the products must be only salt and water.
Option D: Sodium hydroxide is a base, but oxygen is an element, not an acid. They do not undergo a neutralization reaction to form salt and water.

Visual 1: Diagram: General Acid-Base Neutralization. A simple diagram showing an acid (containing H⁺ ions) and a base (containing OH⁻ ions) mixing to form water (H₂O) and a salt (composed of the remaining cation and anion).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Acid-base neutralization reactions and their products as background academic context rather than a clinical decision trigger.
Understanding acid-base reactions is fundamental to comprehending human physiology, particularly the body's buffer systems that maintain blood pH within the narrow range of 7.35-7.45.
Many medications are based on neutralization principles. For example, antacids are bases (like magnesium hydroxide or calcium carbonate) that neutralize excess stomach acid (hydrochloric acid) to relieve heartburn and indigestion.
What if? If a patient has metabolic acidosis (low blood pH), the body's primary buffer system, the bicarbonate-carbonic acid system, works to neutralize the excess acid. The kidneys also compensate by excreting more acid (H⁺) and generating more bicarbonate (HCO₃⁻).

How to Approach the Question

First, identify the core requirement of the question: the reaction must produce only salt and water.
Recognize this as the definition of a specific type of chemical reaction: an acid-base neutralization.
Analyze each option by classifying the reactants as acid, base, or other substance.
Option A: Acid + Acidic Oxide. This is not a neutralization reaction.
Option B: Acid + Base. This is a potential neutralization reaction. Predict the products: Sulfuric acid (H₂SO₄) + Potassium hydroxide (KOH) → Potassium sulfate (K₂SO₄) + Water (H₂O). This matches the requirement.
Option C: Acid + Carbonate (a type of base). Recall that acid-carbonate reactions produce salt, water, AND carbon dioxide gas. This disqualifies it.

Concept Tested & Keywords

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