UPSC CISF-AC-EXE Archives

31. Which one among the following is not a west-flowing river?

Which one among the following is not a west-flowing river?

Mahi

Banas

Luni

Sabarmati

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Most peninsular rivers in India flow eastwards into the Bay of Bengal, primarily due to the general eastward slope of the Deccan Plateau. However, some prominent rivers flow westwards into the Arabian Sea, including the Narmada and Tapti, which flow through rift valleys. Other west-flowing rivers listed in the options are Mahi, Luni, and Sabarmati, which drain into the Arabian Sea or the Rann of Kutch. The Banas River is a major river in Rajasthan. It is a tributary of the Chambal River, which itself is a tributary of the Yamuna River. The Yamuna joins the Ganges, which flows eastwards into the Bay of Bengal. Therefore, the Banas River is not a west-flowing river; it flows generally northeast/east before joining the Chambal.

The Banas River is a tributary of the Chambal, which flows towards the east-draining into the Bay of Bengal system, unlike Mahi, Luni, and Sabarmati which are west-flowing rivers.

The Luni river is unique among the options as it is an inland river; it flows into the Rann of Kutch and does not reach the Arabian Sea. The Mahi River flows through Madhya Pradesh, Rajasthan, and Gujarat, and drains into the Arabian Sea. The Sabarmati River originates in the Aravalli Range of Rajasthan and flows southwest across Gujarat into the Arabian Sea.

32. Which one among the following cities in India is located at the Northe

Which one among the following cities in India is located at the Northernmost latitude?

Sri Ganganagar

Nainital

Gangtok

Itanagar

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To determine the northernmost city, we need to compare their approximate latitudes.
Sri Ganganagar (Rajasthan) is located near the northern border of Rajasthan, close to Punjab. Its approximate latitude is around 29.9° N.
Nainital (Uttarakhand) is a hill station. Its approximate latitude is around 29.4° N.
Gangtok (Sikkim) is located in the Eastern Himalayas. Its approximate latitude is around 27.3° N.
Itanagar (Arunachal Pradesh) is in Northeast India. Its approximate latitude is around 27.1° N.
Comparing these values (29.9° N, 29.4° N, 27.3° N, 27.1° N), Sri Ganganagar has the highest latitude, making it the northernmost city among the options.

The latitude of a place determines its north-south position. A higher northern latitude means the location is further north.

While Srinagar, Jammu and Kashmir, is a major northern city in India, it was not among the options. Understanding the relative geographical positions of states like Rajasthan, Uttarakhand, Sikkim, and Arunachal Pradesh helps in estimating the likely latitudes of cities within them. Northern Rajasthan is generally located at higher latitudes than parts of Uttarakhand, Sikkim, and Arunachal Pradesh.

33. Match List-I with List-II and select the correct answer using the code

Match List-I with List-II and select the correct answer using the code given below the Lists :

List-I
(Natural disaster)

List-II
(Category)

A. Blizzards	1. Terrestrial
B. Soil erosion	2. Atmospheric
C. Tsunami	3. Biological
D. Locusts	4. Aquatic

Code :

A-3, B-4, C-1, D-2

A-3, B-1, C-4, D-2

A-2, B-1, C-4, D-3

A-2, B-4, C-1, D-3

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Matching the natural disasters with their categories:
A. Blizzards are severe snowstorms characterized by strong winds, which are atmospheric phenomena. Thus, Blizzards (A) match with Atmospheric (2).
B. Soil erosion is the denudation of the upper layer of soil, a process occurring on the Earth’s surface, hence a terrestrial phenomenon. Thus, Soil erosion (B) matches with Terrestrial (1).
C. Tsunami is a series of giant waves caused by large-scale disturbances, most commonly underwater earthquakes or volcanic eruptions. As it is a phenomenon related to water bodies, it is categorized as aquatic. Thus, Tsunami (C) matches with Aquatic (4).
D. Locusts are migratory insects that form swarms and can cause massive damage to crops. This involves biological organisms causing a disaster, hence a biological phenomenon. Thus, Locusts (D) match with Biological (3).
The correct matching is A-2, B-1, C-4, D-3, which corresponds to option C.

Natural disasters can be broadly categorized based on their origin, such as atmospheric, terrestrial, aquatic, and biological.

Other examples include: Atmospheric (cyclones, droughts, heat waves), Terrestrial (earthquakes, landslides, volcanic eruptions), Aquatic (floods, storms, sea-level rise), Biological (epidemics, pest infestations). Some disasters can overlap categories or have cascading effects across categories.

34. Consider the following statements regarding landscape : 1. Bhabar is

Consider the following statements regarding landscape :

1. Bhabar is a narrow belt ranging between 8 km-10 km parallel to the Shiwalik foothills at the break-up of the slope.
2. Bhabar is a belt consisting of old and new alluvial deposited by rivers.

Which of the statements given above is/are correct?

1 only

2 only

Both 1 and 2

Neither 1 nor 2

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Statement 1 is correct. The Bhabar belt is indeed located south of the Shiwalik hills, parallel to the foothills. It is a narrow zone, typically 8-16 km wide (the range 8-10 km provided is within this range), and it consists of pebbles and boulders deposited by rivers descending from the mountains. The porosity of the Bhabar causes rivers to disappear underground here. Statement 2 is incorrect. The Bhabar belt is characterized by coarse deposits (pebbles, boulders). The concept of “old and new alluvial” deposits primarily applies to the plain regions south of the Bhabar, specifically the Bhangar (older alluvium forming terraces) and Khadar (newer alluvium forming floodplains).

Bhabar is a porous belt of pebbles and boulders parallel to the Shiwaliks where rivers disappear, not a region of old and new alluvial deposits.

The physical divisions of the Northern Plains, from north to south, are typically identified as Bhabar, Tarai, Bhangar, and Khadar. The Tarai is a wet, marshy region south of the Bhabar where the underground rivers reappear. The Bhangar is the older alluvial plain above the flood level, and the Khadar is the newer alluvial plain within the flood level.

35. Which one among the following elements has the highest catenation

Which one among the following elements has the highest catenation property?

Silicon

Carbon

Nitrogen

Oxygen

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Catenation is the ability of an element to form bonds with atoms of the same element. Carbon has the strongest tendency for catenation among all elements. This property allows carbon atoms to link together to form long chains, branched structures, and rings, forming the backbone of the vast number of organic compounds.

Carbon exhibits the highest catenation property among elements, forming diverse organic structures.

Silicon also shows catenation, forming silanes (Si-Si bonds), but the Si-Si bond is weaker than the C-C bond, limiting the length and stability of silicon chains compared to carbon chains. Nitrogen can form chains (e.g., in hydrazine, N₂H₄), but N-N bonds are relatively weak. Oxygen primarily forms chains of two atoms (O-O bond in peroxides), and longer chains are generally unstable. The high strength of the C-C bond and carbon’s ability to form multiple bonds (single, double, triple) contribute to its exceptional catenation ability.

36. Rhizobium is a

Rhizobium is a

biopesticide

biofertilizer

bioherbicide

mycoherbicide

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Rhizobium is a genus of bacteria known for forming a symbiotic relationship with the roots of leguminous plants. Within root nodules, these bacteria fix atmospheric nitrogen (N₂) and convert it into a form usable by plants (ammonia/ammonium), thereby enriching the soil and providing essential nutrients for plant growth. This process makes Rhizobium a type of biofertilizer.

Rhizobium bacteria fix atmospheric nitrogen, acting as a natural fertilizer for plants, especially legumes.

Biofertilizers are substances containing living microorganisms which, when applied to seed, plant surfaces, or soil, colonize the rhizosphere or the interior of the plant and promote growth by increasing the supply or availability of primary nutrients to the host plant. Biopesticides, bioherbicides, and mycoherbicides are types of pesticides or herbicides derived from natural materials (e.g., bacteria, fungi, plants, minerals) used to control pests or weeds.

37. A solution has a pH value around 13.0. The solution may be called

A solution has a pH value around 13.0. The solution may be called

a strong acid

a strong base

neutral

a weak acid

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The pH scale measures the acidity or basicity of an aqueous solution. The scale ranges typically from 0 to 14. Solutions with a pH less than 7 are acidic, a pH of 7 is neutral, and solutions with a pH greater than 7 are basic (alkaline). A pH value around 13.0 is significantly greater than 7 and is close to the maximum value on the scale, indicating a highly basic solution.

A pH value of 13.0 indicates a strong base because it is high on the pH scale (greater than 7).

Strong acids have very low pH values (close to 0 or 1), weak acids have pH values between 1 and 7, neutral solutions have a pH of 7, weak bases have pH values between 7 and 14, and strong bases have very high pH values (close to 13 or 14). Examples of strong bases include sodium hydroxide (NaOH) and potassium hydroxide (KOH).

38. Which one of the following is an example of a physical change?

Which one of the following is an example of a physical change?

Ripening of banana

Souring of milk

Melting of ice

Passing CO₂ gas into water

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Melting of ice is a physical change because it involves a change of state from solid water (ice) to liquid water. The chemical composition of the substance remains H₂O throughout the process; only its physical form changes. Physical changes are typically reversible.

A physical change alters the form or appearance of a substance but not its chemical composition.

Ripening of banana and souring of milk are examples of chemical changes because they involve chemical reactions that result in the formation of new substances with different chemical properties (e.g., sugars converting to acids, proteins and sugars breaking down). Passing CO₂ gas into water leads to the formation of carbonic acid (H₂CO₃), which is also a chemical change. Chemical changes are often irreversible.

39. The chemical formula of washing soda is

The chemical formula of washing soda is

NaHCO₃

Na₂CO₃

Na₂CO₃·10H₂O

NaOCl

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Washing soda is the common name for hydrated sodium carbonate. Its chemical formula is Na₂CO₃·10H₂O, which represents sodium carbonate decahydrate. This compound is widely used as a cleaning agent and in various industrial processes.

Washing soda is chemically known as sodium carbonate decahydrate (Na₂CO₃·10H₂O).

Option A, NaHCO₃, is the chemical formula for baking soda (sodium bicarbonate). Option B, Na₂CO₃, is anhydrous sodium carbonate, also known as soda ash. Option D, NaOCl, is the chemical formula for sodium hypochlorite, the main ingredient in many household bleaches.

40. Which one of the following human cells is devoid of a nucleus?

Which one of the following human cells is devoid of a nucleus?

Nerve cell

Bone cell

Red blood cell

White blood cell

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Mature mammalian red blood cells (erythrocytes) are unique among human cells in that they lack a nucleus, as well as other organelles like mitochondria, ribosomes, and endoplasmic reticulum. This adaptation allows them to maximize the space available for hemoglobin, the protein responsible for oxygen transport, and also makes them more flexible to squeeze through narrow capillaries.

Mature red blood cells are anucleated, meaning they are devoid of a nucleus.

While mature red blood cells in mammals lack a nucleus, this is not the case for red blood cells in birds, reptiles, amphibians, and fish, which retain their nuclei. Nerve cells, bone cells, and white blood cells are all nucleated cells that perform various functions in the body, such as transmitting electrical signals, providing structural support, and fighting infections, respectively.