Q.Why does shifts in demand curve occur for a commodity ?

The demand curve slopes downward from left to right (negative slope).

With price on the Y-axis and quantity demanded on the X-axis, the standard demand curve slopes downward, reflecting the Law of Demand: other things (income, tastes, prices of related goods) remaining constant, consumers buy more of a good when it is cheaper and less when it is costlier — due to the substitution effect, income effect, and (in the cardinal-utility view) the law of diminishing marginal utility. 'Upward sloping' would represent the rare exceptions (Gi …

A leftward shift of demand for a normal good is caused by a fall in consumer income — option (c).

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All the listed factors reduce supply, so the answer is (D) All of these.

Supply falls (the curve shifts left) for several reasons. A rise in the cost of production makes each unit less profitable, so firms supply less (A). A rise in the prices of substitutes in production tempts producers to switch resources to those other goods, cutting the supply of this good (B). A fall in the number of firms in the industry directly lowers tot …

A simultaneous rightward shift of demand and supply raises quantity but leaves the price change indeterminate, so (D) is correct.

In the RBSE/CBSE Class-12 market-equilibrium chapter, when BOTH the demand curve and the supply curve shift to the right:

• Quantity — unambiguously increases (both shifts push quantity up).
• Price — the two shifts pull in opposite directions. A rightward demand shift tends to raise price, while a rightward supply shift tends to lower it.

The net effect on price therefore depends on the relative size of the two shifts:

• If demand shifts more than supply → price rises.
• If supply shifts more than demand → price falls. …

Equal rightward shifts of both the demand and supply curves raise the equilibrium quantity while leaving the equilibrium price unchanged.

Market equilibrium occurs where the demand curve intersects the supply curve. When a rise in demand (demand curve shifts right by Δ) is matched EXACTLY by an equal rise in supply (supply curve shifts right by the same Δ) at the original price, both curves move outward by the same horizontal distance:

• At the OLD equilibrium price, there is no longer excess demand or excess supply, because both quantity demanded and quantity supplied have risen by the same amount — so the price does not need to adjust. …

An increase in taxation decreases supply.

A tax (such as an excise or indirect tax) raises the cost of production per unit for the seller. At the existing price the producer now earns less, so at every price he is willing to supply a smaller quantity. This causes the supply curve to shift to the left — i …

The demand curve slopes downward (negative slope) from left to right.

This negative slope reflects the Law of Demand: holding income, tastes, and the prices of related goods constant, a higher price for a good discourages consumers from buying as much of it (due to the substitution effect, income effect, and diminishing marginal utility of successive units), while a lower price encourages them to buy more. Plotted with price on the Y-axis and quantity demanded on the X-axis, this gives a curve sloping downward from the upper-left to the lower-right. (A small number of exceptions — Veblen/prestige goods …

Technological progress causes a rightward shift of the supply curve.

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Perishable goods spoil quickly and cannot be stored long — e.g. milk and vegetables.

Perishable goods are commodities that decay or lose their usefulness in a short time and therefore cannot be stored for long periods; they have to be consumed or sold quickly. Because their supply cannot be easily held back, their market price is often very sensitive to day-to-day changes in supply and demand.

Two clear examples are:

1. Milk — spoils within a day or two without refrigeration. …

Change in demand = a shift of the whole demand curve due to non-price factors.

Demand for a good depends on its own price and on other determinants: income, tastes and preferences, prices of related (substitute/complementary) goods, and expectations. 'Change in quantity demanded' refers only to movement ALONG a fixed demand curve when the good's own price changes. 'Change in demand', by contrast, means the entire curve shifts to a new position because one of the non-price determinants changes — e.g., a rise in income shifts the demand curve for a normal good to the right (increase in demand), while an adverse chan …