UPSC 2021: Nexus 71—80

Universal Solvents, Relativistic Constants, Chemical Toxins & Constitutional Liberty. [Set A]

Question 71

Chemical Physics

Water can dissolve more substances than any other liquid because

(a) it is dipolar in nature
(b) it is a good conductor of heat
(c) it has high value of specific heat
(d) it is an oxide of hydrogen

Official Verdict: (a) it is dipolar in nature

The Core Concept: Water ($H_2O$) possesses an asymmetric bent molecular geometry with oxygen pulling shared electrons far more greedily than hydrogen. This creates a permanent electrical separation: a partial negative charge ($\delta^-$) on the oxygen crown and partial positive charges ($\delta^+$) on the hydrogen arms. This powerful dipolar nature enables water to wedge itself between positive and negative ions of salts and polar compounds, tearing them apart and hydrating them individually—earning its crown as the "universal solvent."

Tethered to: REALM 06: Chemical Bonding

Question 72

Illumination Photonics

With reference to street-lighting, how do sodium lamps differ from LED lamps?

Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps.
As street-lights, sodium lamps have longer life span than LED lamps.
The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street-lighting.

Select the correct answer using the code given below.

Official Verdict: (c) 1 and 3 only

The Core Concept: Statement 1 is true: High-pressure and low-pressure sodium lamps radiate light omnidirectionally in all 360 degrees (requiring reflectors), whereas solid-state LEDs are directional emitters emitting focused light at 180 degrees or less. Statement 2 is false: LEDs boast a operational lifespan of 50,000+ hours, vastly outlasting sodium discharge lamps (~18,000–24,000 hours). Statement 3 is true: Low-pressure sodium produces a monochromatic yellow emission line (around 589 nm), obliterating night color perception, while broad-spectrum white LEDs offer a high Color Rendering Index (CRI).

Tethered to: REALM 85: The EM Spectrum

Question 73

Cellular Virology

The term 'ACE2' is talked about in the context of

(a) genes introduced in the genetically modified plants
(b) development of India's own satellite navigation system
(c) radio collars for wildlife tracking
(d) spread of viral diseases

Official Verdict: (d) spread of viral diseases

The Core Concept: ACE2 stands for Angiotensin-Converting Enzyme 2. While its physiological job is regulating blood pressure and cardiovascular inflammation, it rocketed to global prominence during the COVID-19 pandemic. The SARS-CoV-2 coronavirus employs its surface spike protein like a lockpick, binding specifically to the ACE2 receptor on human epithelial cells (lungs, heart, gut) to fuse with the cell membrane and initiate viral infection.

Tethered to: REALM 298: Infectious & Vector-Borne

Question 74

Polymer Chemistry

Bisphenol A (BPA), a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics?

(a) Low-density polyethylene
(b) Polycarbonate
(c) Polyethylene terephthalate
(d) Polyvinyl chloride

Official Verdict: (b) Polycarbonate

The Core Concept: Bisphenol A (BPA) is condensed with phosgene or diphenyl carbonate to synthesize polycarbonate plastics—shatter-resistant, clear, rigid materials commonly found in refillable water jugs, baby bottles, and safety goggles. It is also used to formulate epoxy resin can liners. Because BPA is an endocrine-disrupting chemical that mimics estrogen, it leaches from polycarbonate into consumables under heat or wear.

Tethered to: REALM 40: Synthetic Polymers

Question 75

Chemical Toxicology

'Triclosan', considered harmful when exposed to high levels for a long time, is most likely present in which of the following?

(a) Food preservatives
(b) Fruit-ripening substances
(c) Reused plastic containers
(d) Toiletries

Official Verdict: (d) Toiletries

The Core Concept: Triclosan is a synthetic chlorinated aromatic antimicrobial and antifungal preservative widely incorporated into personal hygiene toiletries—specifically antibacterial soaps, body washes, deodorants, and toothpastes (to reduce gingivitis). Chronic high-level bioaccumulation causes endocrine disruption, alters gut microbiota, and accelerates antimicrobial resistance (AMR), leading regulatory bodies like the US FDA to restrict its use in consumer wash products.

Tethered to: REALM 51: Chemicals in Everyday Life

Question 76

Relativistic Physics

Which one of the following is a reason why astronomical distances are measured in light-years?

(a) Distances among stellar bodies do not change.
(b) Gravity of stellar bodies does not change.
(c) Light always travels in straight line.
(d) Speed of light is always same.

Official Verdict: (d) Speed of light is always same.

The Core Concept: In Einstein's special relativity, the speed of light in a vacuum ($c \approx 299,792,458\ m/s$) is a universal, invariant constant that never changes, regardless of the observer's motion or the light source. Because all other cosmic variables fluctuate (stellar bodies actively move in an expanding universe, gravity varies, and gravitational lensing curves light paths), the invariant speed of light makes the distance light travels in one Julian year ($9.46 \times 10^{12}\ km$) the ultimate cosmic yardstick.

Tethered to: REALM 61: Special & General Relativity

Question 77

Comparative Constitutional Law

We adopted parliamentary democracy based on the British model, but how does our model differ from that model?

As regards legislation, the British Parliament is supreme or sovereign but in India, the power of the Parliament to legislate is limited.
In India, matters related to the constitutionality of the Amendment of an Act of the Parliament are referred to the Constitution Bench by the Supreme Court.

Select the correct answer using the code given below.

Official Verdict: (c) Both 1 and 2

The Core Concept: Both statements are correct. 1: In the UK, parliamentary sovereignty reigns supreme with no written constitution or judicial strike-down powers (Dicey's doctrine). In India, constitutional supremacy prevails: Parliament's legislative power is restricted by Fundamental Rights, federal federal legislative lists, and the Basic Structure doctrine. 2: Under Article 145(3) of the Constitution of India, any case involving a substantial question of law regarding constitutional interpretation or the validity of an amendment is heard by a Constitution Bench comprising a minimum of five Supreme Court judges.

Tethered to: REALM 10: Parliamentary vs Presidential

Question 78

Administrative Machinery

With reference to the Union Government, consider the following statements:

N. Gopalaswamy Iyengar Committee suggested that a minister and a secretary be designated solely for pursuing the subject of administrative reform and promoting it.
In 1970, the Department of Personnel was constituted on the recommendation of the Administrative Reforms Commission, 1966, and this was placed under the Prime Minister's charge.

Which of the statements given above is/are correct?

Official Verdict: (b) 2 only

The Core Concept: Statement 1 is false: The N. Gopalaswamy Ayyangar Report (1949) focused on reorganizing the Central Secretariat into balanced ministerial bureaus and civil service cadre structuring, not establishing an exclusive Minister/Secretary solely for administrative reform. Statement 2 is true: The First Administrative Reforms Commission (headed by Morarji Desai, then K. Hanumanthaiah) recommended establishing a separate personnel agency; accordingly, in 1970, the Department of Personnel was created directly within the Cabinet Secretariat under the Prime Minister's direct portfolio.

Tethered to: REALM 175: Administrative Reform

Question 79

Fundamental Rights Jurisprudence

'Right to Privacy' is protected under which Article of the Constitution of India?

(a) Article 15
(b) Article 19
(c) Article 21
(d) Article 29

Official Verdict: (c) Article 21

The Core Concept: In the landmark nine-judge unanimous bench ruling of Justice K.S. Puttaswamy (Retd.) vs. Union of India (2017), the Supreme Court held that the Right to Privacy is a fundamental right that emanates directly from the Right to Life and Personal Liberty guaranteed under Article 21, as well as the overarching freedoms in Part III. It protects personal autonomy, spatial privacy, and informational data privacy.

Tethered to: REALM 35: Article 21

Question 80

Electoral Laws & Precedents

Consider the following statements:

In India, there is no law restricting the candidates from contesting in one Lok Sabha election from three constituencies.
In 1991 Lok Sabha Election, Shri Devi Lal contested from three Lok Sabha constituencies.
As per the existing rules, if a candidate contests in one Lok Sabha election from many constituencies, his/her party should bear the cost of bye-elections...

Which of the statements given above is/are correct?

Official Verdict: (X) Dropped Question

The Core Concept: UPSC officially dropped this question from scoring due to framing ambiguities. Historically: Under Section 33(7) of the Representation of the People Act, 1951 (amended in 1996), a candidate is strictly restricted to contesting a maximum of two constituencies (Statement 1 is false). In 1991 (prior to the 1996 cap), former Deputy PM Devi Lal did contest from three Lok Sabha seats (Sikar, Rohtak, and Ferozepur). Statement 3 is false: The Election Commission has repeatedly proposed that candidates or parties bear the cost of vacated bye-elections, but no such rule has ever been enacted into law.

Tethered to: REALM 150: Representation of the People Act, 1951