UPSC CISF-AC-EXE Archives

11. Which one of the following crops is not a Kharif crop?

Which one of the following crops is not a Kharif crop?

Rice

Maize

Wheat

Soya bean

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Wheat is a Rabi crop, not a Kharif crop.

Kharif crops are sown during the monsoon season (roughly June-July) and harvested in autumn (September-October). Rabi crops are sown in winter (October-November) and harvested in spring (March-April). Rice, Maize, and Soya bean are typical examples of Kharif crops grown during the monsoon season in India.

Major Rabi crops include Wheat, Barley, Gram, Mustard, and Peas. Other Kharif crops include Jowar, Bajra, Cotton, Jute, Groundnut, etc.

12. The Silent Valley is located in which one of the following States?

The Silent Valley is located in which one of the following States?

Himachal Pradesh

Jammu and Kashmir

Jharkhand

Kerala

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The Silent Valley National Park is located in the state of Kerala, India.

Silent Valley is located in the Nilgiri Hills and is known for its unique evergreen forests and biodiversity. It gained prominence due to a major environmental movement in the 1970s and 1980s to protect it from a proposed hydroelectric project.

It is part of the Western Ghats, a UNESCO World Heritage Site. The park is home to many endangered species, including the Lion-tailed Macaque.

13. Which one of the following is not a female reproductive organ of

Which one of the following is not a female reproductive organ of flower?

Style

Ovary

Pollen

Stigma

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Pollen is the male gametophyte of a flower.

The female reproductive part of a flower is called the pistil or carpel, typically consisting of three parts: the stigma (receives pollen), the style (stalk connecting stigma to ovary), and the ovary (contains ovules, which develop into seeds). The male part is the stamen, consisting of the anther (produces pollen) and the filament.

Style, Ovary, and Stigma are all components of the pistil/carpel, which constitutes the female reproductive organ(s) of a flower. Pollen grains are produced by the anthers, which are part of the male reproductive organs (stamens).

14. Which one of the following cell organelles synthesizes its own protein

Which one of the following cell organelles synthesizes its own proteins involving genes present in its DNA?

Endoplasmic reticulum

Plasma membrane

Plastid

Lysosome

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Plastids (like chloroplasts) contain their own DNA and ribosomes and can synthesize some of their own proteins.

Mitochondria and plastids are unique among eukaryotic organelles because they possess their own circular DNA (similar to bacterial DNA) and ribosomes (70S type). This allows them to synthesize some of the proteins required for their function, independently of the cell’s nucleus and cytoplasmic ribosomes.

The endoplasmic reticulum is involved in protein synthesis and modification but relies on ribosomes attached to it or free in the cytoplasm. The plasma membrane is a structural component. Lysosomes contain enzymes synthesized elsewhere in the cell.

15. Which one of the following is a disease for which India has not faced

Which one of the following is a disease for which India has not faced epidemic at any point of time in the past?

Cholera

Plague

Leukaemia

Swine flu

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Leukaemia is a type of cancer affecting blood cells and does not occur in epidemic form.

Epidemics refer to a widespread occurrence of an *infectious disease* in a community at a particular time. Cholera and Plague are historical infectious diseases that have caused major epidemics in India. Swine flu (H1N1) is a viral infectious disease that has also caused outbreaks in India.

While cancer rates can vary regionally or over time, it is not an infectious disease and does not spread from person to person in a way that causes epidemics. The term “epidemic” is specific to infectious diseases.

16. In which part of the heart and circulatory system of human body does d

In which part of the heart and circulatory system of human body does deoxygenated blood flow?

Aorta

Pulmonary vein

Left atrium

Vena cava

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Deoxygenated blood from the body flows into the right side of the heart via the Vena Cava.

The circulatory system involves two main loops: the systemic circulation (body) and the pulmonary circulation (lungs). Deoxygenated blood returns from the body via the superior and inferior vena cava to the right atrium, then to the right ventricle, which pumps it to the lungs.

Oxygenated blood returns from the lungs via the pulmonary veins to the left atrium, then to the left ventricle, which pumps it to the body via the aorta. Therefore, the aorta, pulmonary vein (carrying blood *from* lungs), and left atrium all carry oxygenated blood (with the pulmonary artery and vena cava carrying deoxygenated blood as key exceptions to the typical vein/artery oxygenation rule).

17. Which one of the following statements is correct?

Which one of the following statements is correct?

Euplectella and Spongilla belong to different phyla of Animalia.

Sea anemone belongs to phylum Echinodermata.

Holothuria is a member of phylum Mollusca.

Scolopendra (Centipede) is a member of phylum Arthropoda.

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Scolopendra (Centipede) is indeed a member of the phylum Arthropoda.

Arthropoda is the largest phylum in the animal kingdom and includes insects, spiders, crustaceans, and myriapods (like centipedes and millipedes). Centipedes belong to the class Chilopoda within Arthropoda.

Let’s analyze the other options: A) Euplectella and Spongilla are both types of sponges and belong to the phylum Porifera, so they are in the same phylum. B) Sea anemones belong to the phylum Cnidaria (or Coelenterata), not Echinodermata. C) Holothuria (Sea cucumber) belongs to the phylum Echinodermata, not Mollusca.

18. Catalytic converter transforms waste gases from the engines of many ca

Catalytic converter transforms waste gases from the engines of many cars into carbon dioxide, nitrogen and water. The catalyst is made of

platinum and copper

molybdenum and copper

platinum and rhodium

rhodium and molybdenum

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Catalytic converters use precious metals like platinum, palladium, and rhodium as catalysts to convert harmful exhaust gases into less harmful substances.

Platinum and rhodium are commonly used together in catalytic converters, particularly in three-way converters, which target carbon monoxide (CO), unburnt hydrocarbons (HC), and nitrogen oxides (NOx).

Platinum is effective for oxidizing CO and HCs. Rhodium is effective for reducing NOx. Palladium is also used, often in conjunction with platinum, and is effective for oxidizing CO and HCs. Copper and molybdenum are not typically used as the primary catalysts in automotive catalytic converters.

19. The number of elements in the lanthanoids of the periodic table is

The number of elements in the lanthanoids of the periodic table is

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The number of elements in the lanthanoids of the periodic table is 14.

The lanthanoids (or lanthanides) are a series of chemical elements comprising the 15 elements from lanthanum (atomic number 57) through lutetium (atomic number 71). However, the term “lanthanoid series” usually refers to the 14 elements immediately following Lanthanum, from Cerium (atomic number 58) to Lutetium (atomic number 71), as these are the elements where the 4f subshell is progressively filled. Lanthanum itself has the electron configuration [Xe] 5d¹ 6s², not filling the 4f subshell, but it is chemically similar to the other lanthanoids and is often included in the series or considered the first element.

In the context of the f-block of the periodic table, which is typically displayed as two rows below the main body, the lanthanoids constitute the upper row. This row consists of 14 elements, starting after Barium (Z=56) and before Hafnium (Z=72) in the main table. These 14 elements are Cerium (58), Praseodymium (59), Neodymium (60), Promethium (61), Samarium (62), Europium (63), Gadolinium (64), Terbium (65), Dysprosium (66), Holmium (67), Erbium (68), Thulium (69), Ytterbium (70), and Lutetium (71).

Given the options, 14 is present and is the standard number of elements represented in the f-block lanthanoid series, corresponding to the filling of the 4f orbitals. While the definition can sometimes include Lanthanum (making it 15), 14 is the number that fits the typical arrangement and f-orbital filling.

The actinoids are the second series in the f-block, starting from Actinium (Z=89) or Thorium (Z=90) up to Lawrencium (Z=103), also containing 14 elements where the 5f subshell is filled. The lanthanoids and actinoids are sometimes collectively called the inner transition metals.

20. Out of the elements phosphorus (P), sulphur (S), chlorine (Cl) and flu

Out of the elements phosphorus (P), sulphur (S), chlorine (Cl) and fluorine (F), the elements having the most negative and least negative electron gain enthalpy, respectively are

Cl and P

F and S

F and Cl

P and S

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The elements having the most negative and least negative electron gain enthalpy among P, S, Cl, and F, respectively, are Cl and P.

Electron gain enthalpy is the energy change when an electron is added to a neutral gaseous atom to form a negative ion. A negative value means energy is released, indicating the atom has an affinity for electrons. A more negative value signifies a stronger affinity.
We are comparing P (Group 15), S (Group 16), Cl (Group 17), and F (Group 17).
General trends:
– Across a period (left to right), electron gain enthalpy generally becomes more negative (atoms become smaller and nuclear charge increases, attracting the added electron more strongly). Group 18 (noble gases) have positive electron gain enthalpies as they have a stable electron configuration. Group 15 elements have relatively less negative (or slightly positive) values due to the stability of the half-filled p-subshell.
– Down a group, electron gain enthalpy generally becomes less negative (the added electron is further from the nucleus in a larger shell and experiences more shielding).

Let’s consider the given elements:
– F (Period 2, Group 17)
– Cl (Period 3, Group 17)
– S (Period 3, Group 16)
– P (Period 3, Group 15)

Comparing F and Cl (Group 17): Although the general trend is less negative down a group, Cl has a more negative electron gain enthalpy (-349 kJ/mol) than F (-328 kJ/mol). This is an anomaly due to the very small size of F, where the added electron experiences significant repulsion from existing electrons in the compact 2p subshell.
Comparing Cl and S (same period, different groups): Electron gain enthalpy becomes more negative across the period. Cl is in Group 17, S is in Group 16. So, Cl should have a more negative value than S. (Cl: -349 kJ/mol, S: -200 kJ/mol). This is consistent.
Comparing S and P (same period, different groups): S is in Group 16, P is in Group 15. Group 15 elements have unusually low (less negative) electron gain enthalpies due to the stable half-filled configuration. So, P should have a less negative value than S. (S: -200 kJ/mol, P: -74 kJ/mol). This is consistent.

Ranking the elements by electron gain enthalpy from most negative to least negative:
Cl (-349) > F (-328) > S (-200) > P (-74)

The element with the most negative electron gain enthalpy is Cl.
The element with the least negative electron gain enthalpy is P.

The pair is (Cl, P).

Electron gain enthalpy can be positive for some elements, meaning energy must be supplied to add an electron. Noble gases typically have positive electron gain enthalpies. Elements in Group 2 (alkaline earth metals) and Group 12 also tend to have values close to zero or positive for the first electron gain enthalpy.