NCERT Class X Science Solutions: Chapter 1 – Chemical Reactions and Equations Part 4 (For CBSE, ICSE, IAS, NET, NRA 2022)


Question 17:



‘X’ is copper () and the black-coloured compound formed is copper oxide () . The equation of the reaction involved on heating copper is given below.

Question 18:

Why do we apply paint on iron articles?



Question 19:




Question 20:

Explain the following terms with one example each.

  1. Corrosion
  2. Rancidity


  1. Corrosion:

Corrosion is defined as a process where materials, usually metals, deteriorate as a result of a chemical reaction with air, moisture, chemicals, etc. For example, iron, in the presence of moisture, reacts with oxygen to form hydrated iron oxide.

This hydrated iron oxide is rust.

This Diagram Shows Hydrated Iron Oxide is Rust
  1. Rancidity:


For example, the taste and smell of butter changes when kept for long. Rancidity can be avoided by:

  1. Storing food in air tight containers
  2. Storing food in refrigerators
  3. Adding antioxidants
  4. Storing food in an environment of nitrogen