UPSC CAPF Archives

1. Which one of the following functions as an automatic stabilizer in the

Which one of the following functions as an automatic stabilizer in the context of fiscal and monetary policies of an economy?

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Personal income tax

Reverse repo rate of bank

Open market operation

Bond price

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UPSC CAPF – 2021

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Personal income tax functions as an automatic stabilizer because tax revenue automatically increases during economic booms (as incomes rise) and decreases during recessions (as incomes fall), helping to moderate the business cycle without requiring explicit policy changes.

Automatic stabilizers are government programs or policies that counteract the business cycle automatically. During an economic downturn, they stimulate the economy by increasing spending or reducing taxes (e.g., unemployment benefits, progressive income tax). During an upturn, they restrain the economy by decreasing spending or increasing taxes.

Reverse repo rate and open market operations are tools of monetary policy used by the central bank, requiring deliberate action (discretionary policy), not automatic adjustment. Bond prices are market outcomes, not policy tools acting as stabilizers. Other examples of automatic stabilizers include corporate profit taxes and welfare benefits.

2. How is the magnitude of price elasticity for an individual good

How is the magnitude of price elasticity for an individual good determined?

1, 2 and 3

1 and 4 only

1, 2 and 4

3 and 4

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UPSC CAPF – 2021

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Based on the common factors determining price elasticity and likely intended factors for this question (although the factors 1, 2, 3, 4 were missing in the prompt), the combination of factors 1, 2, and 3 is the most accurate choice among the given options. Assuming factors 1, 2, and 3 refer to the nature of the good (necessity/luxury), availability of substitutes, and proportion of income spent, respectively, these are all significant determinants.

Key factors that determine the price elasticity of demand for a good include: 1. The nature of the good (necessity vs. luxury); 2. The availability and closeness of substitutes; 3. The proportion of income spent on the good; and 4. The time period under consideration (short run vs. long run).

Assuming the original question listed common factors such as ‘Nature of the good’, ‘Availability of substitutes’, ‘Proportion of income spent’, and ‘Time horizon’ corresponding to options 1, 2, 3, and 4, then all four are valid determinants. However, given the provided answer choices, option A (1, 2 and 3) suggests that factors 1, 2, and 3 (likely Nature, Substitutes, and Proportion of income) were considered the primary determinants relevant to the question’s design, or factor 4 (Time horizon) was either different or not included in the intended correct combination.

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3. Which one of the following properties decreases across the periodic ta

Which one of the following properties decreases across the periodic table from left to right and increases from top to bottom?

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Ionization energy

Electron affinity

Electronegativity

Atomic radius

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UPSC CAPF – 2021

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Atomic radius decreases across the periodic table from left to right and increases from top to bottom.

Across a period (left to right), the atomic radius decreases because the nuclear charge increases while electrons are added to the same energy shell, pulling the electron cloud closer to the nucleus. Down a group (top to bottom), the atomic radius increases because new electron shells are added, increasing the distance between the nucleus and the valence electrons, despite the increased nuclear charge.

Ionization energy, electron affinity (generally), and electronegativity all tend to increase across a period from left to right and decrease down a group from top to bottom, showing the opposite trend to atomic radius. This is because these properties are related to the attraction between the nucleus and electrons; a smaller radius generally means a stronger attraction.

4. Manganese is extracted by heating manganese dioxide with aluminium pow

Manganese is extracted by heating manganese dioxide with aluminium powder. Which one of the following statements with regard to the reaction is correct?

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The reaction is exothermic.

The reaction is endothermic.

Manganese is produced as a solid.

Manganese is more reactive than aluminium.

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UPSC CAPF – 2021

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The reaction between manganese dioxide and aluminium powder is a type of thermite reaction. Thermite reactions are highly exothermic, releasing a significant amount of heat.

Thermite reactions involve the reduction of a metal oxide by a more reactive metal (typically aluminium). The general form is Metal Oxide A + Metal B → Metal A + Oxide of Metal B, where Metal B is more reactive than Metal A. These reactions are characterized by their high exothermicity, often producing molten metal.

In this specific reaction, Al is more reactive than Mn, displacing it from MnO2. The equation is 3MnO₂ + 4Al → 2Al₂O₃ + 3Mn + Heat. While Manganese is indeed produced as a solid at room temperature, during the reaction itself, the high temperature can cause the product metal (depending on its melting point and the reaction’s heat) to be in a molten state. However, the statement that the reaction is exothermic is a fundamental property of this reaction type.

5. Which one of the following metals produces hydrogen with cold water?

Which one of the following metals produces hydrogen with cold water?

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Silver

Sodium

Copper

Iron

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UPSC CAPF – 2021

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Sodium is a highly reactive alkali metal. It reacts vigorously with cold water, producing hydrogen gas and sodium hydroxide.

The reactivity of metals with water varies. Very reactive metals (like Group 1 alkali metals) react with cold water. Less reactive metals (like zinc or iron) may react with steam but not cold water. Even less reactive metals (like copper, silver, gold) do not react with water at all.

The reaction of sodium with cold water is exothermic and can even ignite the hydrogen produced due to the heat generated. The general reaction is 2M + 2H₂O → 2MOH + H₂ (where M is an alkali metal). Other metals like Potassium and Calcium also react with cold water, while Iron reacts with steam to produce iron oxides and hydrogen.

6. Which one of the following metals does not react with oxygen, water or

Which one of the following metals does not react with oxygen, water or acids?

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UPSC CAPF – 2021

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Metals vary widely in their chemical reactivity. Some are highly reactive, readily reacting with oxygen, water, and acids, while others are much less reactive, sometimes referred to as noble metals.

Sodium (Na) is an alkali metal and is extremely reactive, reacting vigorously with oxygen, water, and acids. Copper (Cu) is moderately reactive; it reacts with oxygen to form oxides and with certain acids (like nitric acid or hot sulfuric acid) but is relatively stable in air and water compared to alkali metals. Iron (Fe) is also reactive; it rusts in moist air (reacts with oxygen and water) and reacts with acids. Gold (Au) is a noble metal, known for its low reactivity. It resists reaction with oxygen at normal temperatures, water, and most acids. It can only be dissolved by highly corrosive mixtures like aqua regia (a mixture of nitric acid and hydrochloric acid).

The reactivity series of metals ranks metals according to their reactivity. Gold is very low in the reactivity series, indicating its low tendency to participate in chemical reactions.

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7. Which one of the following pairs is not correctly matched?

Which one of the following pairs is not correctly matched?

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Positively phototropic : Shoot

Positively geotropic : Root

Chemotropic : Pollen tube

Hydrotropic : Flower

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UPSC CAPF – 2021

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Tropisms are directional growth responses of plants to external stimuli. They are named based on the type of stimulus and the direction of growth (positive if towards the stimulus, negative if away).

Positively phototropic growth means growth towards light (e.g., shoots). Positively geotropic growth means growth towards gravity (e.g., roots growing downwards). Chemotropic growth is a response to chemical stimuli (e.g., pollen tube growing towards the ovule guided by chemical signals). Hydrotropic growth is a response to water (e.g., roots growing towards water). Flowers are reproductive structures whose position and development are influenced by factors like light (photoperiodism for flowering) and hormones, but ‘hydrotropism’ is not a primary or characteristic tropic response of flowers themselves. Roots exhibit positive hydrotropism.

Other types of tropism include thigmotropism (response to touch) and thermotropism (response to temperature). The statement ‘Hydrotropic : Flower’ is the incorrectly matched pair as hydrotropism is characteristic of roots.

8. Which one of the following organisms does not possess notochord at any

Which one of the following organisms does not possess notochord at any stage of its life cycle?

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Holothuria

Herdmania

Exocoetus

Salamander

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UPSC CAPF – 2021

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The notochord is a flexible, rod-like structure found in chordates. It provides skeletal support and is usually present during embryonic development, being replaced by the vertebral column in most adult vertebrates.

Holothuria (sea cucumber) belongs to the phylum Echinodermata, which are non-chordates. Therefore, they do not possess a notochord at any stage of their life cycle. Herdmania (sea squirt) is a Urochordate (Tunicate), which is a subphylum of Chordata; it possesses a notochord in its larval stage. Exocoetus (flying fish) is a bony fish (Vertebrata, Chordata); it possesses a notochord during embryonic development, which develops into the vertebral column in the adult. Salamander (Amphibia, Vertebrata, Chordata) also possesses a notochord during embryonic development that is replaced by the vertebral column.

The four key characteristics of chordates are a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail, present at some stage in their life cycle. Echinoderms, such as starfish, sea urchins, and sea cucumbers, are invertebrates and lack these chordate features.

9. Which one of the following statements about life processes in single-c

Which one of the following statements about life processes in single-celled organisms is not correct?

They require separate organ for food uptake.

Separate organ is not needed for respiration.

Waste of excretory material is produced by these organisms.

They remain in contact with external environment.

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UPSC CAPF – 2021

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Single-celled organisms are prokaryotic or eukaryotic organisms consisting of a single cell. All necessary life processes, such as nutrition, respiration, excretion, and reproduction, occur within this single cell.

Unlike multicellular organisms which have specialized organs for specific functions, single-celled organisms perform all functions through the mechanisms available within that single cell. Food uptake in organisms like Amoeba occurs through processes like phagocytosis or pinocytosis across the cell membrane, not through a separate organ. Gaseous exchange for respiration and elimination of waste materials occur directly through diffusion across the cell surface, which is in direct contact with the external environment.

The large surface area to volume ratio in single-celled organisms facilitates efficient exchange of materials, nutrients, gases, and waste products directly with their surroundings, making specialized organs unnecessary.

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10. Which one of the following is not a function of chlorophyll?

Which one of the following is not a function of chlorophyll?

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Splitting of water

Absorption of photon

Oxidation of carbohydrate

Conversion of light energy into chemical energy

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UPSC CAPF – 2021

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Chlorophyll is the primary pigment involved in photosynthesis in plants, algae, and cyanobacteria. It is located in chloroplasts and absorbs light energy necessary for the process.

Chlorophyll’s main functions in photosynthesis include the absorption of light energy (photons), initiation of the light-dependent reactions which include the splitting of water molecules (photolysis) to produce oxygen, protons, and electrons, and facilitating the conversion of light energy into chemical energy in the form of ATP and NADPH. The oxidation (breakdown) of carbohydrates, such as glucose, to release energy (ATP) is the process of cellular respiration, which occurs in mitochondria (or cytoplasm/cell membrane in some organisms) and is distinct from the function of chlorophyll and photosynthesis.

Photosynthesis involves two main stages: the light-dependent reactions, where light energy is captured and converted into chemical energy (ATP and NADPH) and water is split; and the light-independent reactions (Calvin cycle), where the chemical energy is used to fix carbon dioxide and synthesize carbohydrates. Chlorophyll is directly involved in the light-dependent reactions.