NCERT Class 7 Mathematics Ganita Prakash-II: Chapter 7 — Finding the Unknown
This chapter, 'Finding the Unknown' from NCERT's Class 7 Mathematics Ganita Prakash-II, introduces students to the concept of solving for unknown quantities, particularly in the context of weights and balance scales. It presents various scenarios with weighing scales where some weights are known and others are unknown. Students are guided to use logical reasoning and the principle of maintaining balance by removing equal weights from both sides to determine the unknown values. The chapter encourages discussion and justification of answers among classmates, fostering a deeper understanding of algebraic concepts through practical examples. It aims to build foundational skills in problem-solving and algebraic thinking essential for CBSE mathematics.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 7 |
| Subject | Mathematics |
| Book | Ganita Prakash-II |
| Chapter | Chapter 7 — Finding the Unknown |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 1 minute |
| Word count | 127 |
Learning outcomes
- Understand the concept of unknown quantities in mathematical problems.
- Apply the principle of balance to solve for unknown weights.
- Use logical reasoning to determine unknown values in given scenarios.
- Develop problem-solving skills related to algebraic equations.
- Justify mathematical solutions with clear reasoning.
Vocabulary
| Word | Meaning |
|---|---|
| Unknown | A quantity or value that is not known or cannot be measured. |
| Weight | A measure of how heavy something is. |
| Weighing scale | A device used to measure weight. |
| Balanced | In a state of equilibrium; not tipping to one side. |
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Practice questions
- If a weighing scale is balanced with 5 kg on one side and an unknown weight 'x' on the other, what is the value of 'x'? Answer: x = 5 kg
- In a balance scale, if we remove 2 kg from both sides that are currently balanced, will the scale remain balanced? Answer: Yes, the scale will remain balanced.
- If a sack weighs 's' kg and two sacks balance with 10 kg, what is the weight of one sack? Answer: 2s = 10 kg, so s = 5 kg
Frequently asked questions
What is the main concept taught in Chapter 7 of NCERT Class 7 Mathematics Ganita Prakash-II?
Chapter 7, 'Finding the Unknown', teaches students how to solve for unknown quantities, particularly weights, using balance scales and logical reasoning.
How does a weighing scale help in finding unknown weights?
A weighing scale demonstrates the principle of balance. By understanding that removing equal weights from both sides maintains balance, students can deduce the value of unknown weights.
What mathematical principle is used to solve problems in this chapter?
The chapter uses the principle of equality and balance, which is fundamental to solving algebraic equations. If two sides are equal, removing the same value from both sides keeps them equal.
Why is it important to discuss answers with classmates?
Discussing answers helps students understand different approaches to problem-solving and reinforces their reasoning by explaining their thought process to others.
What kind of problems are presented in the 'Math Talk' section?
The 'Math Talk' section presents problems involving sacks of unknown but equal weights, requiring students to determine the weight of a single sack using the balance scale principle.
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NCERT Class 7 Mathematics — Ganita Prakash-II — Chapter 7 — Finding the Unknown. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.