NCERT Solutions for Class 9th Social Science Chapter 9 End-of-chapter exercise — Questions and activities

Refute the statement — the word that makes it wrong is “always”. The chapter's own wording is deliberately careful: “A rise in income generally makes people feel more confident about their ability to spend, so the quantity demanded for several goods rises, even if prices remain the same.” Generally and several are not always and all.

What is true. A rise in income does raise purchasing power, and for most goods a family will then buy more at the same price. Note what kind of change this is:

Why “always” fails — three reasons drawn from the chapter.

Start from the one relationship the whole question turns on: petrol and a petrol car are complementary goods — you cannot use one without the other. So when petrol doubles, the cost of running a petrol car doubles, and the demand for petrol cars falls. Everything else follows from that.

(a) His cost of production falls — and it falls twice over. He uses 40 per cent less water, so that part of his cost drops directly. And the same field now yields 30 per cent more, so whatever he does spend is spread over more kilograms.

This is the chapter's own point about technology: “Improvement in technology reduces the cost of production, allowing producers to produce more and supply more.” Drip irrigation is named in the book itself.

(b) He is willing to supply more at every price — his supply curve shifts to the right. Cheaper production means a price that was barely worth accepting before is now comfortably profitable. Say he was willing to sell 100 kg at ₹20 a kg; with his lower cost per kilogram he would supply that 100 kg at a lower price, and at ₹20 he would now offer 130 kg.

(c) If many farmers adopt it, market supply rises sharply and the equilibrium moves — to a lower price and a larger quantity. Market supply is the sum of individual supplies, so if most sellers each offer 30 per cent more, the market supply curve S shifts right to S₁.

Step by step: at the old price the extra output creates a surplus; unsold crop pushes the price down; the lower price brings in more buyers (a movement down along D) and discourages the least efficient sellers (a movement down along S₁); the market settles at E₁.

Sellers cut prices during festival sales because a much larger quantity sold at a smaller margin can earn more than a small quantity sold at a large one — and the festival season is exactly when that trade pays off.

Why sellers do it — four reasons from the chapter's own concepts.

• Seasonality has already raised demand. The festive season is on the chapter's list of demand determinants: “customers flocking to sweet shops during the festive season”. Many more buyers are in the market at that moment, so a discount reaches far more people than the same discount in June.
• Buyers are waiting for it. “People delay buying durables before Diwali or the New Year, expecting festival discounts.” Once buyers postpone, present demand falls — and the only way to bring it back is to hold the sale they are waiting for.
• Old stock must be cleared. Last season's clothes and last year's phone model lose value once new stock arrives, so selling them cheaply is better than holding them.
• Many sellers compete on one platform. The chapter notes that more sellers mean higher competition and lower prices; on an online marketplace a buyer can compare prices in seconds, so no seller can hold out.

What happens to the equilibrium — and this needs care, because two different things are often confused.

Does it benefit only consumers? No — both sides gain, in different ways.

But not every seller gains equally. A seller with a thin margin, or one who must match a large competitor's discount to stay visible, may sell more and still earn less. That is the same warning the chapter gives about the number of sellers: more competition brings the price down, and the sellers who cannot bear the lower price are the ones who leave the market.

The answer is (b) Shortage. A maximum price fixed below the market price is a price ceiling — “an imposed price control that sets the maximum amount a seller can charge”. Below equilibrium, buyers want more than sellers are willing to supply, and the gap is excess demand.

What that shortage looks like in practice: vaccination centres run out of stock, waiting lists and queues appear, doses have to be rationed by rule rather than by price, and — as the chapter records for sanitisers in 2020 — some sellers may resort to hoarding and black marketing, selling illegally above the cap.

Why the other three options are wrong:

Method. Look for prices that are printed, notified or capped rather than bargained. Three good places to search: the maximum retail price printed on any packaged good, the fare charts displayed at bus stands and railway stations, and any notified minimum — the minimum wage board's rates displayed at a worksite. For each one you find, record three things: is it a maximum or a minimum, who is being protected, and what would happen without it.

What a good answer must contain: examples you can point to, sorted into the chapter's two categories — a price ceiling (a maximum, protecting buyers) and a price floor (a minimum, protecting sellers or workers) — plus the reason for each. Note that the tobacco and alcohol case in the question is a third kind: a tax, which raises the price rather than fixing it.

Sample answer, built from the chapter's own examples.

The reasons sort into four kinds.

• Affordability of essentials. Markets allocate by willingness and ability to pay, so an unregulated price can put a necessity beyond the reach of low-income households.
• Protecting the weaker side of a bargain. A minimum wage is a floor because an individual worker has little bargaining power against an employer.
• Preventing exploitation during shortages. Hoarding and black-marketing appear exactly when a good is scarce and urgently needed.
• Discouraging harmful consumption. Here a high tax is used because the Law of Demand works: a higher price reduces quantity demanded.

Yes — and the chapter devotes a whole section to it, while being equally clear that some regulation is necessary. Its exact position: “Although government regulations are required when markets are inefficient, they must be implemented carefully, as excessive government intervention can have adverse effects.” The problem is never regulation as such; it is regulation that is too heavy, too rigid, or left in place after the need has passed.

The three harms, with the chapter's own examples.

Notice the chain in each case. The harm is never the rule itself but what the rule does to behaviour: a capped price changes what a farmer plants; a stack of clearances changes whether a young person opens a restaurant at all; a ceiling on returns changes whether anyone buys a better seed. Regulation acts on incentives, and incentives decide supply.

The other half of the balance, which a complete answer must include. The same chapter shows regulation working. The sanitiser price cap of 2020 protected consumers during a genuine emergency and, because new firms could enter quickly, supply rose and sanitisers “soon became widely available at fair prices”. Regulators such as RBI, CCPA, TRAI and SEBI keep markets transparent without setting prices at all. Public goods — roads, streetlights, sanitation — exist only because the government provides them.

Method. Fill your own column first, honestly, moving down the price list: at ₹100 a kilogram, how much guava would you buy in a week? At ₹80? At ₹50? At ₹20? Then ask each of three friends the same four questions without showing them your answers, so their numbers are their own. Add across each row to get the Total column — that total is the market demand of your little four-person market, exactly as Table 9.1 sums Srivalli, Alex and Israt.

What a good answer must contain: (i) every column showing quantity rising as price falls — if any column falls, ask that friend again, because something other than price has crept in; (ii) a Total column that is the exact sum of the four; (iii) four individual graphs plus one market graph, all with price on the y-axis and quantity on the x-axis; and (iv) a sentence noting that the market curve is flatter than any individual curve, and why.

Sample answer (your own numbers will differ — that is the point of the exercise):

What the graphs show. Every curve slopes downward — that is the Law of Demand appearing in real answers rather than in a textbook. And the total curve is much flatter: the price fall from ₹100 to ₹20 adds 4 kg to my own demand but 16 kg to the market's, because four people are responding instead of one. That is precisely the point made in the DON'T MISS OUT box on page 198.

Method. Go early, and go again in the evening. Carry a small notebook and record the price of three or four vegetables at both visits. Then ask two or three sellers the same three questions, and one or two buyers as well — the two sides often give different answers, and the difference is itself part of the answer. Useful questions to ask a seller: where did you buy this stock and at what rate? what do you do with what is left at closing time? what happened to prices after the last rain?

What a good answer must contain: the prices you actually recorded, at least one seller's own words, and an explanation that uses demand and supply rather than blaming any one person.

(a) Who decides the prices? Nobody, and everybody. This is the point most students get wrong. The seller quotes a price, but he cannot choose it freely.

• Below him is a floor: the rate he paid at the wholesale market or mandi that morning, plus his transport and the day's rent. He cannot sell below that for long.
• Above him is a ceiling: what the seller in the next stall is charging. Buyers can simply walk four steps, so no seller can hold a price much above the others.
• Between them, bargaining. Buyers ask for less, sellers ask for more, and the price that day settles where the vegetables actually clear.

So the price is decided by the interaction of demand and supply, exactly as the chapter says: “prices are determined by the interaction between demand and supply”, through “negotiation between what buyers are willing to pay and what sellers are willing to accept”.

(b) Why are prices sometimes very high and sometimes very low? Because the supply of vegetables swings sharply while demand stays fairly steady.

(c) Why tomatoes are dearer in the morning and cheaper by evening. Yes — this is easy to verify, and the reason lies with the seller's position rather than the tomato's.

Apply one test to each pair: are they used together, or does one replace the other? The chapter's definitions do all the work — substitutes “can replace each other”, complements “are generally used together to provide utility to the consumer”.

Summing up:

Here is Fig. 9.8 redrawn to the same scale, so every reading below can be checked against it.

a. What does point E represent? E is the market equilibrium — the one point where the demand curve DD’ cuts the supply curve SS’, so the quantity demanded equals the quantity supplied. At E there is neither a shortage nor a surplus: the market is ‘cleared’, and there is no pressure on the price to move.

b. The equilibrium price and quantity. Drop a line from E to the x-axis and it meets it at 30 kg. Draw a line from E to the y-axis and it meets it halfway between the ₹200 and ₹300 marks, that is, about ₹250.

c. Points A and B, and the gap between them. Both lie on the upper dashed line, which is at ₹300 — a price above equilibrium.

• A is on DD’, so A tells us the quantity demanded at ₹300: reading down from A, roughly 23 kg. Buyers want less at this higher price than they did at ₹250 — they have moved up along the demand curve.
• B is on SS’, so B tells us the quantity supplied at ₹300: roughly 37 kg. Sellers offer more at this higher price — they have moved up along the supply curve.
• The gap A→B is excess supply — a surplus of about 37 − 23 = 14 kg. That much is brought to market and left unsold.

d. Points F and C, and the gap between them. Both lie on the lower dashed line, a price below equilibrium (a little above ₹150 on the scale).

• F is on DD’, giving the quantity demanded at this lower price: roughly 43 kg. Cheaper mangoes attract more buyers.
• C is on SS’, giving the quantity supplied at that price: roughly 18 kg. Sellers offer far less when the price is low.
• The gap C→F is excess demand — a shortage of about 43 − 18 = 25 kg. That much is wanted and simply not available.

e. If the price stays at the lower dashed line, what happens next in a free market? It will not stay — the shortage itself pushes it up.

If instead the price were held there by force — a price ceiling — the shortage would not disappear. It would show up as queues, rationing and, as the chapter records for sanitisers in 2020, possibly hoarding and black-marketing.

First, a correction the data forces on us. As printed, the Q.D. row rises with price (5, 10, 15, 20, 25) and the Q.S. row falls (25, 20, 15, 10, 5). That is the exact opposite of the two laws this chapter has just established — the Law of Demand is an inverse relationship and the Law of Supply a direct one. The two rows have clearly been interchanged in printing. The schedule that matches the chapter is:

Note that the equilibrium is the same either way — at ₹30 both quantities are 15 kg — but only this reading gives a downward demand curve and an upward supply curve, and only this reading makes part (c) come out consistent with the chapter.

a. The plot. Price on the y-axis, quantity on the x-axis; five points for each curve.

b. The equilibrium. Run down the two rows until the numbers match.

c. What happens at ₹20 and at ₹40.