NCERT Solutions for Class 9th Social Science Chapter 9 The Price Puzzle: What Drives the Market
Updated on 2026-09-19
About this chapter
Demand is the quantity of a product people are willing and able to buy at a particular price. Willingness alone is not demand — it must be backed by purchasing power . The Law of Demand is the inverse relation between price and quantity demanded: Srivalli buys 1 kg at ₹150, 2 kg at ₹100 and 3 kg at ₹50 (Fig. 9.2), which is why the demand curve DD’ slopes downward. Market demand is the sum of all individual demands. Table 9.1 adds Srivalli, Alex and Israt: at ₹150 → 1+2+3 = 6 kg, at ₹100 → 2+4+6 = 12 kg, at ₹50 → 3+6+9 = 18 kg. Because many buyers respond together, the market demand curve D m D m ’ is flatter than any one buyer's curve. Price is only one determinant. Demand also changes with the price of related goods (substitutes like tea and coffee; complements like cars and petrol), inco
- Chapter opening
- The chapter's opening paragraph
- Demand
- Other Determinants of Demand
- Other Determinants of Supply
- Market Equilibrium
- Does Market Equilibrium Exist in the Real World?
- Regulation of Unfair Practices
- Role of Government in the Economy
- Provision of Public Goods
Quick revision
| Term | What it means | Where it appears in the chapter | What the chapter says about it |
|---|---|---|---|
| Demand | The quantity of a product people are willing and able to buy at a particular price | Page 196, section Demand | Depends on needs, preferences, season, trend and income; it is willingness plus ability to pay |
| Purchasing power | A measure of how much one unit of a currency can buy at a particular time | Page 196, margin | Desire alone is not demand — it must be backed by purchasing power |
| Law of Demand | Price up → quantity demanded down; price down → quantity demanded up | Page 196, Fig. 9.1 | The inverse relationship between price and quantity demanded; it is why DD’ slopes downward |
| Individual demand | What one consumer wants to buy at different prices, other things constant | Page 196, Fig. 9.2 | Srivalli: 1 kg at ₹150, 2 kg at ₹100, 3 kg at ₹50 |
| Demand schedule / demand curve | The table of price–quantity pairs, and the same table drawn as a graph | Page 196, Fig. 9.2 (a) and (b) | Points A, B and C joined give the downward-sloping line DD’ |
| Market demand | The sum of all individual demands at each price | Page 197, Table 9.1 | Q1+Q2+Q3 → 6 kg at ₹150, 12 kg at ₹100, 18 kg at ₹50 |
| Related goods | Goods whose demand is interconnected | Page 198, margin | A change in the price or availability of one directly affects demand for the other |
| Substitute goods | Goods that can replace each other | Page 198 | Tea and coffee; if coffee gets dearer, demand for tea rises |
| Complementary goods | Goods generally used together | Page 198 | Smartphones and earphones; cars and petrol; cinema tickets and popcorn |
| Diminishing marginal utility | The extra usefulness from each additional unit falls as more is consumed | Page 199, THINK ABOUT IT | The first mango is delicious, the fourth is not — so willingness to pay falls and demand falls |
| Supply | The quantity sellers are willing and able to offer at a particular price | Page 200, section Supply | Higher prices raise profitability, so output rises and new firms are attracted |
| Law of Supply | Price up → quantity supplied up; price down → quantity supplied down | Page 200, Fig. 9.4 | A direct relationship, giving an upward-sloping supply curve |
| Market supply | The sum of all individual supplies at each price | Page 201, Table 9.2 | A+B+C → 6 kg at ₹50, 12 kg at ₹100, 18 kg at ₹150 |
| Market equilibrium | The point where quantity supplied equals quantity demanded | Page 203, margin and Table 9.3 | Equilibrium price ₹100, equilibrium quantity 12 kg; the market is ‘cleared’ |
| Excess demand (shortage) | Quantity demanded is more than quantity supplied at that price | Page 203, Table 9.3 | At ₹40, Qd = 38 kg against Qs = 6 kg |
| Excess supply (surplus) | Quantity supplied is more than quantity demanded at that price | Page 203, Table 9.3 | At ₹150, Qs = 43 kg against Qd = 8 kg |
| Revenue | Total money a business earns from sales before expenses are deducted | Page 205, margin | Hotels change tariffs several times a day to earn maximum revenue |
| Price ceiling | An imposed control setting the maximum a seller may charge | Page 206, margin | Used on essential goods like medicines to prevent overcharging |
| Price floor | An imposed limit on how low a price may be | Page 206, margin | A minimum wage is a price floor; to be effective it must be set above the equilibrium price |
| Monopoly | A market with a single seller controlling the entire supply of a unique product | Page 206, margin | May charge higher prices, give poorer quality and restrict supply, so the government keeps it in check |
| Hoarding | Accumulating goods or money beyond what is immediately necessary | Page 207, margin | Driven by fear of shortages, expected price rises or speculation — seen during COVID-19 |
| Black marketing | Illegal trade in goods and services that are banned or regulated | Page 207, margin | Followed the sanitiser stockouts of 2020 |
| Public goods | Goods and services provided by the government for all citizens | Page 207 | Roads, bridges, parks, streetlighting, defence, sanitation — private firms avoid them as they earn no direct profit |
| Ease of doing business | How simple it is to start, run and close a business in a country | Page 208, margin | Measured by regulations, bureaucratic efficiency and legal frameworks |
Exercises
- Chapter opening — The Big Questions Page 195
- The chapter's opening paragraph — In-text Questions Page 195
- Demand — DON'T MISS OUT Page 198
- Other Determinants of Demand — THINK ABOUT IT Page 199
- Other Determinants of Demand — LET'S EXPLORE Page 200
- Other Determinants of Supply — LET'S EXPLORE Page 203
- Market Equilibrium — LET'S ANALYSE Page 204
- Does Market Equilibrium Exist in the Real World? — THINK ABOUT IT Page 205
- Regulation of Unfair Practices — THINK ABOUT IT Page 206
- Role of Government in the Economy — In-text Questions Page 206
- Regulation of Unfair Practices — DON'T MISS OUT Page 207
- Provision of Public Goods — LET'S EXPLORE Page 207
- Limitations of Government Intervention — LET'S RECALL Page 208
- The chapter's recap points, with the evidence behind each — Before we move on… Page 209
- End-of-chapter exercise — Questions and activities Page 210–213