NCERT Solutions for Class 9th Social Science Chapter 9 Chapter opening — The Big Questions
Book page 195 Updated on2026-09-08
Q1.
What are the factors that influence the demand for and supply of goods and services in a market?
Answer
Price is the first factor on both sides — but it works differently from all the others, and the chapter is careful about the difference. A change in the good's own price moves a buyer or seller along the existing curve. Every other factor changes how much people want to buy or sell at the same price, so it shifts the whole curve. Getting this right is the whole skill of the chapter.
Left: only the price of mangoes changed, so Srivalli slides down her own curve. Right: her income rose (or coffee got dearer, or the festival season began) — she now buys more at every price, so the curve itself moves to D₁.
What influences demand. The chapter lists these in the section ‘Other Determinants of Demand’ (pages 198–200).
Expect a demand boom → produce more; expect weak demand → cut production
Potato wholesalers hold back stock now to sell later at higher prices
Input costs, weather, disasters
Costlier inputs, resource depletion, bad weather or a disaster reduce supply; a cheaper alternate input raises it
Listed in the LET’S EXPLORE box on page 203
Why the distinction matters: if the price of mangoes falls and Srivalli buys more, her demand has not increased — she has simply moved down the same curve. Her demand increases only when she is willing to buy more at the same ₹150, and that needs something else to change: her income, her taste, the season, the price of bananas, or what she expects prices to do next.
Q2.
How are prices of goods and services determined through demand and supply interactions?
Answer
The price settles where the quantity buyers want to buy exactly equals the quantity sellers want to sell. The chapter puts it as a negotiation: “Every market involves negotiation between what buyers are willing to pay and what sellers are willing to accept.” Any other price leaves one side disappointed, and their pressure moves the price.
The chapter's own mango numbers show it. Table 9.1 gives market demand and Table 9.2 gives market supply at the same three prices:
Price
Market demand QD
Market supply QS
Which is bigger
What happens to the price
₹150
1+2+3 = 6 kg
3+7+8 = 18 kg
QS > QD — surplus of 12 kg
Mangoes are left unsold and will rot; sellers cut the price
₹100
2+4+6 = 12 kg
2+4+6 = 12 kg
QS = QD
No pressure either way — this is the equilibrium
₹50
3+6+9 = 18 kg
1+3+2 = 6 kg
QD > QS — shortage of 12 kg
Buyers compete for too few mangoes; the price is bid up
The market demand and market supply schedules of Tables 9.1 and 9.2 drawn together. Above ₹100 the surplus pushes the price down; below ₹100 the shortage pulls it up. Both arrows lead to E.
Why it happens: at ₹150 the sellers have brought 18 kg but buyers will take only 6 kg. Mangoes are perishable, so a seller left with unsold stock would rather cut the price than throw the fruit away — and each cut brings in more buyers, because a lower price moves buyers down along their demand curve. At ₹50 the opposite happens: 18 kg is wanted and only 6 kg is on offer, so buyers outbid one another and the higher price also draws sellers to offer more. The pressure stops only at ₹100, where the two quantities are equal at 12 kg.
Tip: notice that nobody fixes ₹100. It is not chosen by a seller or announced by an officer — it emerges from thousands of small decisions by buyers and sellers. That is what people mean when they say the market determines the price.
Q3.
What is market equilibrium, and does it exist in the real world?
Answer
Market equilibrium is the point where the supply of goods and services equals demand, so there is neither a surplus nor a shortage and prices tend to remain stable unless external factors change. That is the chapter's own definition (page 203 margin). For the mango market it is ₹100 and 12 kg — the point E where DMDM’ cuts SMSM’ in Fig. 9.7.
At ₹100: Quantity demanded = 12 kg
At ₹100: Quantity supplied = 12 kg
QS = QD → the market is ‘cleared’ Equilibrium price = ₹100 · Equilibrium quantity = 12 kg
And the honest answer to the second half is: not as a resting place. The chapter says so plainly — “‘equilibrium’ in the real world is never stable and moves all the time, i.e., the market is always in a process of adjusting to a new equilibrium, never fully settling at the previous one.” Equilibrium is real as a direction markets move in, not as a place they stay.
The chapter gives two pieces of evidence.
Face masks in 2020. During the COVID-19 pandemic the demand for masks surged rapidly. Supply could not catch up immediately, so prices rose significantly. Over time suppliers adjusted to the higher demand and prices fell. Once the pandemic was over, demand reduced further and prices returned to pre-pandemic levels. Three different equilibria in about two years.
Hotel tariffs in Goa. A 100-room hotel charges ₹1,500 a night on an off-season Monday in July, ₹8,000 on a Saturday in the December tourist season and ₹25,000 on New Year's Eve. If a group tour cancels, the tariff may be cut by 40 per cent overnight to fill the rooms — that is ₹8,000 becoming ₹4,800, or ₹25,000 becoming ₹15,000.
40% of ₹8,000 = ₹3,200 → new tariff = ₹4,800
40% of ₹25,000 = ₹10,000 → new tariff = ₹15,000
Why does the target keep moving? Because the things that fix the two curves keep changing — the chapter lists technology, wages, interest rates, wars, political events, pandemics, weather and natural disasters. Every one of those shifts demand or supply, and a shifted curve means a new intersection.
Why the idea is still worth learning: a compass is useful even though the destination moves. Knowing where equilibrium lies tells you which way the price will move next — if you can see a shortage, expect the price to rise; if you can see unsold stock, expect a discount. That is exactly what the hotel's booking manager is doing when the tariff changes several times in a single day.
Q4.
How and why does the government intervene in the market?
Answer
Because a market allocates goods by willingness and ability to pay, and that is not always a fair way to decide who gets an essential good. The chapter puts the test as a question: “Suppose essential goods like medicines become very expensive, will they be accessible to all?” India, it notes, is a market-based, regulated economy in which prices depend on demand and supply — so the government does not replace the market, it corrects it where it fails.
The three reasons the chapter gives, and the tools used for each:
Why intervene
How the government does it
The chapter's example
Unfair practices and unaffordable essentials
Price ceiling — a maximum price a seller may charge
Maximum prices on essential medicines, to prevent overcharging; sanitisers declared essential commodities under the Essential Commodities Act, 1955, with the maximum retail price capped at ₹100 for a 200 ml bottle
Workers paid too little
Price floor — a lower limit on a price or wage
A minimum wage, “to ensure workers earn enough for their hard work”
Monopoly power
Keeping prices and quantity supplied in check; sector regulators
A single or few dominant sellers can charge more, restrict supply and give poorer quality; RBI for banking, the Central Consumer Protection Authority for consumer rights and unfair trade practices, TRAI for telecommunications, SEBI for the securities market
Goods nobody will supply privately
Provision of public goods — building or funding them from public money
Roads, bridges, public parks, streetlighting, national defence, sanitation and drainage — “usually not provided by private companies because they do not generate direct profit”
The public-goods reason is worth a moment, because the chapter explains it with arithmetic rather than assertion. A neighbourhood park would benefit many families and could be built if each family contributed ₹5,000. But each family reasons: “If others pay, the park will be built anyway, and I can use it without paying.” If enough families think that, not enough money is collected and the park is never built — even though everyone wants it. The good fails not because it is unwanted but because nobody can be excluded from using it once it exists.
The chapter is equally clear that intervention has limits (page 208). Excessive intervention can:
Distort prices and cut producer incentives. If the government fixes wheat at ₹20 per kg when the market price is ₹30, the farmer loses ₹10 on every kilogram — production falls and shortages follow.
Create compliance burdens. A small restaurant may need clearances for food safety, fire safety, pollution control and local permissions; the time and cost can discourage small entrepreneurs.
Discourage innovation. Farmers who cannot earn adequate returns will not invest in better seeds, irrigation or technology, which lowers long-term productivity.
Why both halves matter: the chapter's position is not that intervention is good or bad but that it is a tool with a cost. Regulations “are required when markets are inefficient” and “must be implemented carefully.” A good answer in the examination holds both of those together instead of arguing one side.