NCERT Solutions for Class 10 Science Chapter 14 - Sources of Energy - Free PDF Download
FAQs on NCERT Solutions for Class 10 Science Chapter 14 - Sources Of Energy
1. Is Chapter 14, Sources of Energy, included in the CBSE Class 10 Science syllabus for the 2025-26 board exams?
No, Chapter 14, Sources of Energy, has been removed from the official CBSE Class 10 Science syllabus for the 2025-26 academic year. While these NCERT solutions are provided for students preparing for other competitive exams or for building foundational knowledge, questions from this chapter will not appear in the CBSE board examinations.
2. Where can I find accurate, step-by-step NCERT solutions for all in-text and exercise questions of Chapter 14, Sources of Energy?
You can find reliable and detailed NCERT Solutions for Class 10 Science Chapter 14 on this page. The solutions are prepared by subject matter experts and follow the CBSE guidelines to explain each concept, including definitions, diagrams, and step-by-step problem-solving methods for every question in the textbook.
3. According to the NCERT textbook, what are the qualities of an ideal source of energy?
As per the NCERT solutions for Chapter 14, an ideal source of energy should have the following qualities:
- It should do a large amount of work per unit mass or volume (high calorific value).
- It should be easily accessible and available.
- It must be easy to store and transport.
- It should be economical and affordable.
- It should be safe to handle and use.
- It should cause minimal or no environmental pollution.
4. How do the NCERT solutions explain the disadvantages of using fossil fuels?
The NCERT solutions for Chapter 14 detail the following disadvantages of using fossil fuels:
- Air Pollution: Burning fossil fuels releases harmful gases like carbon dioxide, sulphur dioxide, and nitrogen oxides.
- Acid Rain: The oxides of sulphur and nitrogen can dissolve in rainwater to form acids, leading to acid rain, which damages buildings, soil, and aquatic life.
- Global Warming: The release of greenhouse gases, primarily carbon dioxide, from burning these fuels contributes to the greenhouse effect.
- Non-Renewable: Fossil fuels are a finite resource that takes millions of years to form and are being consumed much faster than they are being replenished.
5. How does the NCERT solution compare biomass and hydroelectricity as sources of energy?
Both biomass and hydroelectricity are considered renewable energy sources, but the NCERT solutions highlight key differences. Biomass energy is derived from organic matter like wood and animal dung (gobar gas), releasing stored chemical energy through combustion. In contrast, hydroelectricity is generated by harnessing the potential energy of water stored at a height in dams, which is then converted into kinetic and finally electrical energy. While biomass utilises chemical energy, hydroelectricity is based on mechanical energy conversion.
6. What type of mirror is best suited for a solar cooker, and what is the NCERT-prescribed reason for this?
The NCERT solution for this question states that a concave mirror is the most suitable for a solar cooker. The reason is that a concave mirror is a converging mirror. It reflects and focuses parallel rays of sunlight onto a single point (the focus). This concentration of solar energy generates a very high temperature, sufficient for cooking food.
7. What are the main limitations of extracting energy from the wind and waves, as outlined in the NCERT exercises?
The NCERT solutions specify distinct limitations for each source:
- Wind Energy: A major limitation is the requirement for a consistent wind speed of over 15 km/h for a windmill's turbine to operate efficiently. Furthermore, setting up a wind farm requires a very large area of land and has a high initial installation cost.
- Wave Energy: To generate electricity from waves, the ocean waves must be very strong and consistent. Viable locations for wave energy farms are limited, and the technology must be robust enough to withstand harsh marine environments.
8. Why does the NCERT solution state that no source of energy can be considered completely pollution-free?
The NCERT solution argues that while some energy sources are cleaner than others, none are truly 100% pollution-free when their entire life cycle is considered. For example, solar cells are often considered non-polluting during operation. However, the manufacturing process of these cells involves materials and energy that can cause environmental damage. Similarly, the disposal of radioactive nuclear waste from nuclear power plants is a significant environmental and health hazard.
9. Based on the NCERT solutions, why is hydrogen considered a cleaner fuel than CNG?
Hydrogen is considered a cleaner fuel than Compressed Natural Gas (CNG) because of its combustion products. CNG is primarily methane (CH₄), a hydrocarbon. When it burns, it produces carbon dioxide (CO₂), a major greenhouse gas. Hydrogen (H₂), on the other hand, produces only water (H₂O) as its byproduct when it combusts or is used in a fuel cell. The absence of carbon in hydrogen fuel means it does not produce any carbon-based pollutants.
10. How has the traditional use of wind and water energy been modified for our convenience, according to Chapter 14?
The NCERT solutions explain that traditional methods have been technologically upgraded for modern needs:
- Water Energy: Traditionally, the kinetic energy of flowing rivers was used for mechanical work like grinding grain. For convenience, we now build large dams to store water, harnessing its potential energy to turn turbines and generate electricity on a massive scale.
- Wind Energy: Previously, windmills were used for mechanical tasks like drawing water. The modern modification involves using the rotatory motion of large blades to spin a generator's turbine, converting wind's kinetic energy directly into electricity for the grid.

















