UPSC CDS-2

11. Consider the following statement: “Atomic number of an element is a mo

Consider the following statement: “Atomic number of an element is a more fundamental property than its atomic mass.” Who among the following scientists has made the above statement?

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Dmitri Mendeleev
Henry Moseley
J.J. Thomson
Ernest Rutherford
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The statement “Atomic number of an element is a more fundamental property than its atomic mass” is a cornerstone of the modern periodic law. This concept was established by Henry Moseley through his experiments on X-ray spectra of elements.
Dmitri Mendeleev developed the periodic table based on atomic mass, but he noted that some elements needed to be placed out of order by mass to fit their chemical properties into the correct groups. Henry Moseley’s work provided the physical basis for this ordering, showing that the frequency of characteristic X-rays emitted by an element is related to its atomic number (the number of protons in the nucleus), which is a more fundamental property determining chemical behaviour than atomic mass.
J.J. Thomson is known for discovering the electron, and Ernest Rutherford is famous for the gold foil experiment which led to the discovery of the atomic nucleus. While both made crucial contributions to atomic structure, it was Moseley who linked atomic number to the properties that govern the periodic table arrangement.

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12. Employing Chromatography, one cannot separate

Employing Chromatography, one cannot separate

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radio-isotopes
colours from a dye
pigments from a natural colour
drugs from blood
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Chromatography is a technique used to separate components of a mixture based on their differential partitioning between a stationary phase and a mobile phase. It is highly effective for separating substances like colours from a dye, pigments from a natural colour, or components like drugs from complex biological matrices such as blood.
Radio-isotopes are different forms of the same element, differing only in the number of neutrons (and thus mass) but having the same chemical properties. Chromatography separates based primarily on physical or chemical interactions that relate to solubility, adsorption, volatility, size, or charge. Since isotopes of an element have virtually identical chemical behaviour, chromatography is generally not a suitable method for separating radio-isotopes. Techniques like mass spectrometry, gas diffusion, or centrifugation are typically used for isotope separation based on mass differences.
While certain specialized chromatographic techniques might theoretically distinguish between isotopes based on subtle differences in physical properties or reaction kinetics, standard chromatography methods are not designed for or capable of effective radio-isotope separation. The question likely refers to standard chromatographic applications.

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13. People prefer to wear cotton clothes in summer season. This is due to

People prefer to wear cotton clothes in summer season. This is due to the fact that cotton clothes are

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good absorbers of water
good conveyors of heat
good radiators of heat
good absorbers of heat
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People prefer to wear cotton clothes in summer primarily because cotton is a good absorber of water (sweat). The absorption of sweat from the body and its subsequent evaporation from the cotton fabric helps to cool the body through evaporative cooling. While cotton also allows air circulation (good conveyor of heat away from body) and radiates heat, its ability to manage sweat is the most significant reason for its preference in hot, humid conditions.
Cotton clothes are preferred in summer due to their good ability to absorb sweat, facilitating evaporative cooling.
Synthetic fabrics like polyester or nylon do not absorb sweat as well, trapping moisture against the skin and making the wearer feel hotter and uncomfortable in summer.

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14. Soap solution used for cleaning purpose appears cloudy. This is due to

Soap solution used for cleaning purpose appears cloudy. This is due to the fact that soap micelles can

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refract light
scatter light
diffract light
polarize light
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Soap solutions, when used for cleaning, form micelles. Micelles are aggregates of soap molecules that are dispersed throughout the water. These aggregates are large enough (typically in the colloidal size range) to scatter light that passes through the solution. This scattering of light, known as the Tyndall effect, makes the solution appear cloudy or opaque.
The cloudy appearance of soap solution is due to the scattering of light by soap micelles (Tyndall effect).
Scattering of light is a characteristic property of colloidal solutions, suspensions, and emulsions, where dispersed particles are larger than the wavelength of light, unlike true solutions where solute particles are too small to scatter visible light.

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15. In graphite, each carbon atom is bonded to three other carbon atoms

In graphite, each carbon atom is bonded to three other carbon atoms

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forming a three-dimensional structure
in the same plane giving a hexagonal array
in the same plane giving a square array
in the same plane giving a pentagonal array
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Graphite has a layered structure. Within each layer, carbon atoms are arranged in a hexagonal lattice, where each carbon atom is covalently bonded to three other carbon atoms in the same plane. These layers are stacked on top of each other and held together by weak van der Waals forces.
Graphite has a layered structure with carbon atoms bonded hexagonally in flat planes.
This layered structure with weak interlayer forces explains graphite’s properties, such as its softness and lubricating ability, which contrast sharply with the hardness of diamond, where carbon atoms form a three-dimensional tetrahedral network.

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16. Which one of the following is monatomic?

Which one of the following is monatomic?

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Hydrogen
Sulphur
Phosphorus
Helium
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A monatomic substance consists of individual atoms that are not bonded together to form molecules under standard conditions. Hydrogen exists as diatomic molecules (H2). Sulphur exists as polyatomic molecules, commonly S8 rings. Phosphorus commonly exists as P4 tetrahedra. Helium is a noble gas and exists as single atoms (He) under standard conditions, hence it is monatomic.
Monatomic substances are composed of single atoms; noble gases like Helium are monatomic.
All noble gases (Helium, Neon, Argon, Krypton, Xenon, Radon) are monatomic under typical conditions because they have stable electron configurations.

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17. Who were Alvars ?

Who were Alvars ?

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Those who immersed in devotion to Vishnu
Devotees of Shiva
Those who worshipped abstract form of God
Devotees of Shakti
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The Alvars were poet-saints of South India who were devout followers of Vishnu (Vaishnavism). Their devotional hymns, compiled as the Divya Prabandha, are central to Vaishnavite tradition. The Nayanars were their counterparts in Shaivism (devotees of Shiva).
Alvars were Vaishnavite Bhakti saints from South India.
There were traditionally 12 Alvars. Their movement flourished between the 6th and 9th centuries CE and played a significant role in the Bhakti movement.

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18. Statement I : The United Provinces during Non-Cooperation became one o

Statement I : The United Provinces during Non-Cooperation became one of the strongest bases of the Congress.
Statement II : The literary outcrop of Non-Cooperation in Bengal was quite meagre compared to the days of the Swadeshi agitation.

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Both the statements are individually true and Statement II is the correct explanation of Statement I.
Both the statements are individually true but Statement II is not the correct explanation of Statement I.
Statement I is true but Statement II is false.
Statement I is false but Statement II is true.
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Statement I is true. The United Provinces (modern Uttar Pradesh) became one of the strongest bases of the Congress during the Non-Cooperation movement, largely due to the active participation of peasant movements, particularly in Oudh, which were integrated into the broader Congress-led struggle. Statement II is also true. While Bengal was active in the Non-Cooperation movement, the period of the Swadeshi agitation (1905-1908) is widely recognized for its intense cultural and literary revival and output as part of the nationalist awakening. Compared to this peak during Swadeshi, the literary output specifically tied to the Non-Cooperation movement in Bengal, while present, is often considered less prolific or intense. Both statements are individually true, but Statement II (literary output in Bengal) does not provide an explanation for Statement I (UP being a strong base).
UP was a major centre for NCM; Swadeshi period had significant literary output in Bengal.
The strength of NCM in UP was also due to the integration of rural issues with the national movement, contrasting with the more urban-centric nature of earlier movements in some other regions.

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19. Statement I : The Oudh Kisan Sabha established in 1920 failed to bring

Statement I : The Oudh Kisan Sabha established in 1920 failed to bring under its wing any Kisan Sabhas.
Statement II : The Oudh Kisan Sabha asked the Kisans to refuse to till bedakhli land, not to offer hari and begar.

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Both the statements are individually true and Statement II is the correct explanation of Statement I.
Both the statements are individually true but Statement II is not the correct explanation of Statement I.
Statement I is true but Statement II is false.
Statement I is false but Statement II is true.
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Statement I is false. The Oudh Kisan Sabha was established in October 1920, partly in response to the feeling that the existing UP Kisan Sabha was dominated by moderates. Its primary aim was precisely to bring the numerous local Kisan Sabhas in Oudh under a unified leadership and banner, which it largely succeeded in doing initially, significantly expanding the peasant movement’s reach. Statement II is true. A key aspect of the Oudh Kisan Sabha’s demands and calls to action included asking peasants to resist exploitative landlord practices such as refusing to cultivate ‘bedakhli’ (land from which tenants were illegally evicted) and refusing to perform ‘hari’ and ‘begar’ (forms of forced labour).
The Oudh Kisan Sabha was formed to unify peasant movements and actively campaigned against landlord exploitation.
Leaders like Jawaharlal Nehru, Baba Ram Chandra, and Madari Pasi were involved in the Oudh peasant movement. Despite initial success, the movement faced internal divisions and government repression.

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20. Statement I : Non-cooperation movement began in Punjab with the studen

Statement I : Non-cooperation movement began in Punjab with the student movement inspired by Lala Lajpat Rai in January 1921.
Statement II : The Sikh dominated central Punjab countryside was stirred by the powerful Akali upsurge.

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Both the statements are individually true and Statement II is the correct explanation of Statement I.
Both the statements are individually true but Statement II is not the correct explanation of Statement I.
Statement I is true but Statement II is false.
Statement I is false but Statement II is true.
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Statement I is false. While the Non-Cooperation movement officially began nationally in January 1921 following the Congress session in December 1920, stating that it *began in Punjab* specifically with *the* student movement inspired by Lala Lajpat Rai in January 1921 is an oversimplification and historically inaccurate. The movement was a national call to action, and Punjab, under leaders like Lala Lajpat Rai, participated actively across various sections, including students. Statement II is true. The Akali movement for the reform of Sikh Gurdwaras was a powerful force in the central Punjab countryside during this period (early 1920s) and significantly stirred the rural population, often aligning or interacting with the broader nationalistic and Non-Cooperation sentiments.
The Non-Cooperation movement was a national initiative from Jan 1921. The Akali movement was a distinct but related movement in Punjab during the same period.
The Akali movement’s mass base and its struggle against the colonial-backed Mahants resonated with the anti-establishment spirit of the Non-Cooperation movement, leading to instances of cooperation and mutual support.

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