Reduction MCQs Quiz | Class 10

This Science (Code 086) quiz covers Unit I: Chemical Substances – Nature and Behaviour for Class X students. The questions focus on the topic of Reduction, including its definition, the concept of it being the reverse of oxidation, and basic identification in chemical reactions. Test your understanding and download the PDF answer sheet for revision.

Understanding Reduction in Chemical Reactions

In Class 10 Science, Unit I, reduction is a fundamental concept often studied alongside oxidation. Together, they form redox reactions. Reduction can be defined in three primary ways depending on the context of the reaction:

  • Loss of Oxygen: If a substance loses oxygen during a reaction, it is said to be reduced. For example, when copper oxide loses oxygen to become copper.
  • Gain of Hydrogen: If a substance gains hydrogen during a reaction, it is said to be reduced.
  • Gain of Electrons: In terms of electronic theory, reduction is defined as the gain of electrons by an atom or ion.

Comparison: Oxidation vs Reduction

Feature Oxidation Reduction
Oxygen Gain Loss
Hydrogen Loss Gain
Electrons Loss Gain

Example Analysis

Consider the reaction: CuO + H2 -> Cu + H2O

Here, Copper Oxide (CuO) loses oxygen to form Copper (Cu). Therefore, CuO is reduced. Hydrogen (H2) gains oxygen to form Water (H2O), so H2 is oxidized.

Quick Revision Points

  • Reduction is the reverse of oxidation.
  • A substance that brings about reduction is called a reducing agent (and is itself oxidized).
  • A substance that undergoes reduction acts as an oxidizing agent.
  • Always look for the movement of Oxygen and Hydrogen first to identify the process in basic equations.