UPSC CAPF Archives

31. Which one of the following metals does not react with oxygen directly?

Which one of the following metals does not react with oxygen directly?

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UPSC CAPF – 2023

Platinum (Pt) is a noble metal known for its low reactivity. It does not react directly with oxygen under normal conditions (room temperature). While it can form oxides under extreme conditions or indirectly, direct oxidation like rusting of iron or tarnishing of silver does not occur easily.

Noble metals, such as Platinum, Gold (Au), and Silver (Ag), are resistant to oxidation and corrosion, which is why they are considered precious metals. Titanium (Ti), Iron (Fe), and Zinc (Zn) are reactive metals that readily react with oxygen to form stable oxides. Titanium forms a passive oxide layer that protects it from further corrosion, but the reaction with oxygen does occur. Iron readily forms rust (iron oxides/hydroxides). Zinc forms a protective layer of zinc oxide/carbonate.

The reactivity of metals with oxygen generally decreases across the periodic table from left to right and down within a group. Noble metals are found towards the right side of the d-block and have high ionization energies and positive standard electrode potentials, making them less likely to lose electrons and react with oxidizing agents like oxygen.

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32. Which one is the most abundant of all the elements on Earth?

Which one is the most abundant of all the elements on Earth?

Silicon

Aluminium

Carbon

Oxygen

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This question was previously asked in

UPSC CAPF – 2023

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Among the given options, Oxygen (O) is the most abundant element on Earth, particularly in the Earth’s crust, which is the most accessible part of the Earth’s solid sphere. By weight, Oxygen makes up about 46.6% of the Earth’s crust.

The elemental composition of the Earth’s crust differs from that of the entire Earth. For the Earth’s crust, the most abundant elements by weight are: Oxygen (O) > Silicon (Si) > Aluminium (Al) > Iron (Fe) > Calcium (Ca) > Sodium (Na) > Potassium (K) > Magnesium (Mg). If considering the entire Earth, Iron is the most abundant element, followed by Oxygen, Silicon, and Magnesium, as the core is primarily composed of iron and nickel.

Silicon is the second most abundant element in the Earth’s crust (about 27.7%). Aluminium is the third most abundant (about 8.1%). Carbon is a crucial element for life but is far less abundant overall compared to Oxygen, Silicon, and Aluminium in the Earth’s crust. Given the options, Oxygen is clearly the most abundant.

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33. Which one of the following statements is not correct regarding the set

Which one of the following statements is not correct regarding the setting of cement?

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The addition of a small percentage of gypsum (CaSO<sub>4</sub>) lengthens the setting period of cement.

According to the colloidal theory, gels of hydrated silicates are formed and when these gels harden, the set cement loses strength.

Tricalcium silicate is responsible for initial setting of cement.

Dicalcium silicate and tricalcium silicate are responsible for the final strength which occurs in about a year.

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UPSC CAPF – 2023

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The incorrect statement is that according to the colloidal theory, gels harden and the set cement loses strength. When the gels formed during the hydration of cement silicates harden, they form a rigid structure that gives the set cement its strength. Therefore, hardening of gels leads to an *increase* in strength, not a loss.

The setting and hardening of cement are complex processes involving the hydration of its components. The colloidal theory describes the formation of hydration products as gels that eventually solidify. Gypsum (CaSO₄·2H₂O) is added to cement clinker to retard the setting time, preventing flash setting and allowing sufficient time for mixing, placing, and finishing. Tricalcium silicate (C₃S) hydrates relatively quickly and is primarily responsible for the initial set and early strength. Dicalcium silicate (C₂S) hydrates slowly and contributes significantly to the long-term strength gain of concrete.

The main components of Portland cement clinker are tricalcium silicate (alite), dicalcium silicate (belite), tricalcium aluminate (celite), and tetracalcium aluminoferrite (ferrite). The hydration reactions of these compounds produce hydrated calcium silicates (C-S-H gel) and calcium hydroxide, which are the main products responsible for binding the aggregates together and providing strength. The C-S-H gel is a colloidal substance that hardens over time.

34. Consider the following redox reaction: 2Cu2O (s) + Cu2S (s) —— 6Cu (s)

Consider the following redox reaction:
2Cu2O (s) + Cu2S (s) —— 6Cu (s) + SO2 (g)
Identify the species among the following acting as oxidant and reductant, respectively:

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Cu(I) and S of Cu2S

Cu and S of SO2

Cu and O of SO2

Cu(I) and O of SO2

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UPSC CAPF – 2023

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In the reaction 2Cu₂O (s) + Cu₂S (s) → 6Cu (s) + SO₂ (g), the oxidation states are as follows:
In Cu₂O, Cu is +1, O is -2.
In Cu₂S, Cu is +1, S is -2.
In Cu, Cu is 0.
In SO₂, S is +4, O is -2.
Cu changes from +1 to 0, so it is reduced. The species causing reduction (oxidant) contains Cu(+1). Both Cu₂O and Cu₂S contain Cu(+1).
S changes from -2 (in Cu₂S) to +4 (in SO₂), so it is oxidized. The species causing oxidation (reductant) is Cu₂S, specifically the S atom within it.
Thus, Cu(I) acts as the oxidant and S of Cu₂S acts as the reductant.

An oxidant (oxidizing agent) is a substance that accepts electrons and is itself reduced. A reductant (reducing agent) is a substance that donates electrons and is itself oxidized. In this reaction, Cu(I) gains electrons to become Cu(0), hence Cu(I) is the oxidant. S(-2) loses electrons to become S(+4), hence S(-2) is the reductant.

This is a self-reduction reaction where the same element (Copper) is present in both reactants and is reduced, while another element (Sulfur) is oxidized. Specifically, Copper from both Cu₂O and Cu₂S is reduced. The sulfur from Cu₂S is oxidized. Therefore, Cu(I) collectively from the reactants acts as the oxidant, and S in Cu₂S acts as the reductant.

35. Pure, demineralized water, free from all soluble mineral salts is obta

Pure, demineralized water, free from all soluble mineral salts is obtained by which of the following method?

Passing water through microfiltration membrane

Calgon’s method

Passing water through a cation exchange and an anion exchange resin bed

By boiling

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This question was previously asked in

UPSC CAPF – 2023

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Pure, demineralized water, free from all soluble mineral salts, is obtained by passing water through a cation exchange and an anion exchange resin bed. This process removes dissolved ions (cations and anions) that constitute mineral salts.

Demineralization or deionization is the process of removing mineral salts from water. Ion exchange is a highly effective method for achieving this. Cation exchange resins replace positive ions (like Ca²⁺, Mg²⁺, Na⁺) with H⁺ ions, and anion exchange resins replace negative ions (like Cl⁻, SO₄²⁻, HCO₃⁻) with OH⁻ ions. The H⁺ and OH⁻ ions then combine to form water (H₂O).

Other options are not suitable for obtaining pure, demineralized water. Microfiltration removes suspended solids but not dissolved salts. Calgon’s method softens water by sequestering hardness ions but doesn’t remove all salts. Boiling removes temporary hardness and dissolved gases but leaves behind permanent hardness salts and other dissolved minerals. Distillation is another method to obtain pure water by separating it from dissolved substances through evaporation and condensation. Reverse osmosis can also produce demineralized water.

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36. Which of the following are the objectives of SAARC? 1. To promote the

Which of the following are the objectives of SAARC?
1. To promote the welfare of the peoples of South Asia and to improve the quality of life
2. To promote and strengthen collective self-reliance among the countries of South Asia
3. To contribute to mutual trust, understanding and appreciation of one another’s problems
4. To work towards ending cross-border terrorism
Select the correct answer using the code given below:

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1 and 2 only

1, 2 and 3 only

1, 2, 3 and 4

3 and 4 only

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UPSC CAPF – 2023

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Statements 1, 2, and 3 are among the objectives of SAARC. Statement 4 is not explicitly listed as a foundational objective in the SAARC Charter.

– Article I of the SAARC Charter lists the following objectives:
– To promote the welfare of the peoples of South Asia and to improve their quality of life. (Statement 1 is correct)
– To accelerate economic growth, social progress and cultural development in the region and to provide all individuals the opportunity to live in dignity and to realize their full potential.
– To promote and strengthen collective self-reliance among the countries of South Asia. (Statement 2 is correct)
– To contribute to mutual trust, understanding and appreciation of one another’s problems. (Statement 3 is correct)
– To promote active collaboration and mutual assistance in the economic, social, cultural, technical and scientific fields.
– To strengthen cooperation with other developing countries.
– To strengthen cooperation among themselves in international forums on matters of common interests.
– To cooperate with international and regional organizations with similar aims and purposes.
– While member countries cooperate on issues like counter-terrorism, “ending cross-border terrorism” is a specific area of cooperation driven by necessity and agreements like the SAARC Regional Convention on Suppression of Terrorism (1987) and Additional Protocol (2004), but it is not listed as one of the main, broad objectives in the original Charter document (Statement 4 is not listed as a core objective).

SAARC was established with the signing of the SAARC Charter in Dhaka on 8 December 1985. Its secretariat is based in Kathmandu, Nepal. The focus of SAARC has historically been on economic, social, and cultural cooperation, though political and security issues, including terrorism, have increasingly become prominent concerns for member states.

37. Which of the following are India’s G20 priorities? 1. Green Developmen

Which of the following are India’s G20 priorities?
1. Green Development
2. Women-led Development
3. Climate Finance
4. Digital Public Infrastructure
Select the correct answer using the code given below:

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1 and 2 only

1, 2 and 3 only

3 and 4 only

1, 2, 3 and 4

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This question was previously asked in

UPSC CAPF – 2023

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All four listed items were among India’s G20 priorities during its presidency (December 2022 – November 2023).

– India’s G20 theme was “Vasudhaiva Kutumbakam” or “One Earth · One Family · One Future”.
– The key priorities highlighted by India included:
– Green Development, Climate Finance, and LiFE (Lifestyle for Environment)
– Accelerated, Inclusive & Resilient Growth
– Accelerating progress on SDGs
– Multilateral Institutions for the 21st Century
– Digital Public Infrastructure (DPI) and Tech-enabled development
– Women-led Development
– All four statements (Green Development, Women-led Development, Climate Finance, Digital Public Infrastructure) align directly with these stated priorities.

India’s G20 presidency focused on addressing global challenges through collective action and fostering consensus among member nations on various critical issues including climate change, sustainable development, technological transformation, and inclusive growth.

38. Which one of the following statements with regard to the impeachment o

Which one of the following statements with regard to the impeachment of a Judge of the Supreme Court of India is not correct?

A motion addressed to the President, signed by at least 100 members of both the Houses of the Parliament is delivered to the Speaker.

The motion is investigated by a Committee of three (2 Judges of the Supreme Court and a distinguished Jurist).

If the Committee finds the Judge guilty of misbehaviour or that he suffers from incapacity, the motion together with the report of the Committee is taken up for consideration in the House where the motion is pending.

The Judge will be removed after the President gives his order for removal.

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UPSC CAPF – 2023

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The incorrect statement with regard to the impeachment of a Judge of the Supreme Court of India is that a motion addressed to the President, signed by at least 100 members of both the Houses of the Parliament is delivered to the Speaker.

– Statement A is incorrect: As per the Judges (Inquiry) Act, 1968, a motion for impeachment must be signed by at least 100 members of the Lok Sabha *or* 50 members of the Rajya Sabha. It is then delivered to the Speaker of the Lok Sabha or Chairman of the Rajya Sabha, respectively. It is not required to be signed by 100 members from *both* Houses collectively for initiation.
– Statement B is correct: If the motion is admitted by the Speaker/Chairman, a three-member committee is constituted to investigate the charges. This committee comprises two Judges of the Supreme Court and a distinguished jurist.
– Statement C is correct: If the Inquiry Committee finds the Judge guilty, the motion along with the Committee’s report is considered by the House where the motion originated.
– Statement D is correct: If the motion is passed by a special majority (two-thirds of members present and voting and a majority of the total membership) in both Houses of Parliament, an address is presented to the President. The Judge is then removed by an order of the President.

The process of impeachment of a Supreme Court Judge (or High Court Judge) is a quasi-judicial procedure. The grounds for removal are proved misbehaviour or incapacity. So far, no judge of the Supreme Court has been successfully impeached and removed, although proceedings have been initiated against some.

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39. Which of the following statements about National Emergency is/are corr

Which of the following statements about National Emergency is/are correct?

1. A Proclamation of Emergency may be made by the President only when the security of India or any part thereof is threatened by war or external aggression or armed rebellion.
2. The Government of India acquires power to give directions to a State on any matter.
3. The Proclamation of Emergency does not suspend the State legislature.
4. The Proclamation of Emergency can continue for a maximum period of six months at a time only if approved by resolutions of both the Houses of Parliament.

1 only

1 and 2 only

1, 2 and 3 only

2, 3 and 4 only

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This question was previously asked in

UPSC CAPF – 2023

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Statements 1, 2, and 3 are correct regarding the National Emergency.

– Statement 1 is correct: Article 352 of the Constitution provides for a National Emergency when the security of India or any part thereof is threatened by war, external aggression, or armed rebellion (originally ‘internal disturbance’, changed by the 44th Amendment Act).
– Statement 2 is correct: During a National Emergency, the executive power of the Union extends to giving directions to any State as to the manner in which its executive power is to be exercised (Article 353(a)).
– Statement 3 is correct: A proclamation of National Emergency does not suspend the State Legislature. State Legislatures continue to function normally, although Parliament acquires concurrent power to make laws on subjects in the State List (Article 250).
– Statement 4 is incorrect: While parliamentary approval makes the Proclamation continue for six months at a time (from the date of approval or subsequent approval), the initial Proclamation is valid for one month *without* parliamentary approval. The statement says it “can continue… only if approved”, which is not entirely accurate for the initial month. More importantly, it can be extended repeatedly for periods of six months after initial approval, implying continuation beyond the first six months is possible with repeated approvals. The phrasing “maximum period of six months at a time only if approved” refers to the duration granted by each approval, but the statement might be interpreted in ways that make it less precise than 1, 2, and 3. Given that 1, 2, and 3 are clearly correct and form an option, it’s most likely intended that 4 is not correct or less accurate in comparison.

A Proclamation of Emergency must be approved by resolutions of both Houses of Parliament within one month from its date of issue. If approved, it continues for six months from the date of approval. It can be extended for further periods of six months with fresh parliamentary approval by a special majority each time.

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40. Which of the following sets of nations are members of the BIMSTEC

Which of the following sets of nations are members of the BIMSTEC Initiative?

Bangladesh, Bhutan, Nepal, India and Sri Lanka

Bangladesh, Bhutan, Nepal, India, Sri Lanka, Thailand and Myanmar

Bangladesh, Bhutan, Nepal, India, Sri Lanka and Maldives

Bangladesh, Bhutan, Nepal, India, Myanmar, Sri Lanka and Indonesia

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This question was previously asked in

UPSC CAPF – 2022

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The set of nations that are members of the BIMSTEC Initiative is Bangladesh, Bhutan, Nepal, India, Sri Lanka, Thailand and Myanmar.

– BIMSTEC stands for the Bay of Bengal Initiative for Multi-Sectoral Technical and Economic Cooperation.
– It is an international organization of seven member states in the littoral and adjacent areas of the Bay of Bengal constituting a contiguous regional unity.
– The member states are five from South Asia (Bangladesh, Bhutan, India, Nepal, Sri Lanka) and two from Southeast Asia (Myanmar, Thailand).

BIMSTEC was founded in 1997. It aims to create an enabling environment for rapid economic development, accelerate social progress, and promote collaboration on matters of common interest in the region. It serves as a bridge between South Asia and Southeast Asia.

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