UPSC CDS-1 Archives

31. 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 (Day)	List-II (Date)
A. World Wetlands Day	1. 29 July
B. International Tiger Day	2. 22 April
C. World Water Day	3. 2 February
D. International Mother Earth Day	4. 22 March

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

This question was previously asked in

UPSC CDS-1 – 2023

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The correct matching of the International Days with their respective dates is: World Wetlands Day (February 2), International Tiger Day (July 29), World Water Day (March 22), International Mother Earth Day (April 22).

– A. World Wetlands Day is observed annually on February 2nd.
– B. International Tiger Day is observed annually on July 29th.
– C. World Water Day is observed annually on March 22nd.
– D. International Mother Earth Day is observed annually on April 22nd.

These are important international days recognized by the United Nations and other organizations to raise awareness about environmental issues and conservation efforts. Knowing the dates helps in following global environmental initiatives.

32. Which one among the following States has the longest extension in nort

Which one among the following States has the longest extension in north-south direction?

Jharkhand

Telangana

Odisha

Chhattisgarh

This question was previously asked in

UPSC CDS-1 – 2023

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Comparing the geographical extents of the given states, Chhattisgarh has the longest extension in the north-south direction.

– The north-south extension corresponds to the latitudinal extent of the state.
– Approximate latitudinal extents:
– Jharkhand: ~21°58’N to 25°18’N (approx. 3°20′)
– Telangana: ~15°46’N to 19°56’N (approx. 4°10′)
– Odisha: ~17°49’N to 22°34’N (approx. 4°45′)
– Chhattisgarh: ~17°46’N to 24°06’N (approx. 6°20′)

Among the options, Chhattisgarh stretches significantly further north from its southern tip compared to the other states, giving it the largest north-south extent. Visual inspection of a map of India or checking precise geographical coordinates confirms this.

33. What will be the correct sequence of cities on the bank of river Ganga

What will be the correct sequence of cities on the bank of river Ganga if someone moves from west to east?

Prayagraj, Kanpur, Bhagalpur, Patna

Prayagraj, Kanpur, Patna, Bhagalpur

Kanpur, Prayagraj, Bhagalpur, Patna

Kanpur, Prayagraj, Patna, Bhagalpur

This question was previously asked in

UPSC CDS-1 – 2023

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The correct sequence of the given cities located on the bank of the River Ganga from west to east is Kanpur, Prayagraj, Patna, Bhagalpur.

– The River Ganga flows generally in an east-south-east direction across the North Indian plains.
– Kanpur is located upstream of Prayagraj (formerly Allahabad).
– Prayagraj is located upstream of Patna.
– Patna is located upstream of Bhagalpur.

Understanding the geographical locations of major cities along prominent rivers is important for general knowledge and geography. The relative positions of these cities along the Ganga reflect the river’s course through Uttar Pradesh, Bihar, and further east.

34. Manav is planning to visit all UNESCO World Heritage Sites in Delhi. H

Manav is planning to visit all UNESCO World Heritage Sites in Delhi. He will be visiting

Red Fort, Qutab Minar, Jama Masjid

Red Fort, India Gate, Qutab Minar

Red Fort, Qutab Minar, Humayun Tomb

Red Fort, Humayun Tomb, India Gate

This question was previously asked in

UPSC CDS-1 – 2023

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Among the options provided, the Red Fort Complex, Qutab Minar and its Monuments, and Humayun’s Tomb are recognized UNESCO World Heritage Sites located in Delhi.

– Red Fort Complex was inscribed as a UNESCO World Heritage Site in 2007.
– Qutab Minar and its Monuments were inscribed as a UNESCO World Heritage Site in 1993.
– Humayun’s Tomb, Delhi was inscribed as a UNESCO World Heritage Site in 1993.
– Jama Masjid and India Gate, although historically and culturally significant landmarks in Delhi, are not currently listed as UNESCO World Heritage Sites.

Delhi has a rich historical legacy with several sites of significant architectural and cultural importance. The three sites mentioned in option C represent distinct periods and architectural styles of India’s history, including the Delhi Sultanate (Qutab Minar) and the Mughal Empire (Humayun’s Tomb, Red Fort).

35. Vicky told his friends about his visit to Stewart Island, Bay of Plent

Vicky told his friends about his visit to Stewart Island, Bay of Plenty and Hawke Bay. Which country did Vicky visit?

Canada

Australia

New Zealand

Ireland

This question was previously asked in

UPSC CDS-1 – 2023

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Stewart Island, Bay of Plenty, and Hawke Bay are all well-known geographical locations within New Zealand.

– Stewart Island is the third-largest island of New Zealand, located south of the South Island.
– The Bay of Plenty is a region on the northern coast of the North Island of New Zealand.
– Hawke Bay is a large bay and a region on the east coast of the North Island of New Zealand.

These locations are distinct geographical features and administrative regions within New Zealand, popular for tourism and their natural beauty. Visiting these places indicates a trip to New Zealand.

36. Which of the following statements are true for the reaction of Fe₂O₃ w

Which of the following statements are true for the reaction of Fe₂O₃ with aluminium?

1. It is known as the ‘thermite reaction’.
2. The heat evolved is used for welding purpose.
3. Aluminium metal acts as an oxidizing agent.
4. Molten Fe and Al are formed at the end of the reaction.

Select the correct answer using the code given below.

1 and 2

1 and 3

2 and 4

1 and 4

This question was previously asked in

UPSC CDS-1 – 2023

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The reaction of Fe₂O₃ with aluminium is a highly exothermic displacement reaction where aluminium, being more reactive than iron, reduces iron(III) oxide to molten iron. The balanced chemical equation is 2Al + Fe₂O₃ → Al₂O₃ + 2Fe + Heat.

– Statement 1 is correct: This reaction is famously known as the thermite reaction.
– Statement 2 is correct: The large amount of heat produced in the thermite reaction results in molten iron, which is used for welding broken railway tracks or cracked machine parts (thermite welding).
– Statement 3 is incorrect: Aluminium acts as a reducing agent because it removes oxygen from Fe₂O₃. Iron(III) oxide (Fe₂O₃) acts as the oxidizing agent.
– Statement 4 is incorrect: Molten iron (Fe) is formed at the end of the reaction. Aluminium is converted to aluminium oxide (Al₂O₃), not molten aluminium metal.

The thermite reaction involves a redox process. Aluminium is oxidized (gains oxygen), and iron is reduced (loses oxygen). The reaction produces a significant amount of heat, reaching temperatures up to 2500°C, which is why the iron is produced in a molten state.

37. Naphthalene burns with a yellow sooty flame. This is because

Naphthalene burns with a yellow sooty flame. This is because

carbon to hydrogen ratio is low

there is incomplete combustion

there is excess supply of air

of presence of impurities of nitrogen and sulfur

This question was previously asked in

UPSC CDS-1 – 2023

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When a substance burns with a yellow, sooty flame, it indicates that combustion is incomplete. Combustion is a chemical process where a substance reacts rapidly with oxygen to produce heat and light. Complete combustion occurs when there is sufficient oxygen, producing primarily carbon dioxide and water. Incomplete combustion occurs when there is insufficient oxygen, leading to the formation of carbon monoxide and/or unburnt carbon particles (soot). The yellow colour of the flame is due to the incandescence (glowing due to heat) of these hot soot particles. Naphthalene (C₁₀H₈) is an aromatic hydrocarbon with a relatively high carbon-to-hydrogen ratio compared to simple alkanes. Compounds with higher carbon content require more oxygen for complete combustion and are more prone to incomplete combustion and soot formation, especially in open air where the oxygen supply may not be perfectly mixed.

– A yellow sooty flame is a characteristic sign of incomplete combustion.
– Incomplete combustion produces soot (unburnt carbon particles) which glow yellow when hot.
– Fuels with a high carbon-to-hydrogen ratio are more likely to produce sooty flames during incomplete combustion.

In contrast, complete combustion typically produces a clean, often blue, flame (as seen in a Bunsen burner with the air hole open or a gas stove flame). Factors affecting the completeness of combustion include the amount of oxygen available, the mixing of fuel and air, and the temperature.

38. Which one of the following is not true for anodizing process?

Which one of the following is not true for anodizing process?

It makes aluminium corrosion resistant.

Metals like aluminium, titanium and magnesium can be anodized.

Clean aluminium article is the anode and oxygen gas is evolved at the cathode.

It is used in aircraft industry.

This question was previously asked in

UPSC CDS-1 – 2023

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Anodizing is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts.
A) It makes aluminium corrosion resistant. This is true. The artificially thickened oxide layer is more robust and protective than the natural oxide layer, providing enhanced corrosion resistance.
B) Metals like aluminium, titanium and magnesium can be anodized. This is true. These are common metals that form stable oxide layers and are frequently anodized.
C) Clean aluminium article is the anode and oxygen gas is evolved at the cathode. In the anodizing process, the aluminium article to be anodized is made the anode (positive electrode). Oxidation occurs at the anode, forming the oxide layer on the aluminium surface. The cathode (negative electrode) is typically an inert material like graphite or lead. At the cathode, reduction occurs, which involves the reduction of water to hydrogen gas and hydroxide ions ($2H_2O + 2e^- \rightarrow H_2 + 2OH^-$) or the reduction of H⁺ ions to hydrogen gas ($2H^+ + 2e^- \rightarrow H_2$). Oxygen gas is evolved at the *anode* if the process involves the electrolysis of water ($2H_2O \rightarrow O_2 + 4H^+ + 4e^-$) as part of the overall reaction, which contributes to the oxide layer formation ($2Al + 3H_2O \rightarrow Al_2O_3 + 6H^+$). However, the primary anodic reaction is the formation of Al₂O₃. Oxygen gas evolution typically occurs at the cathode, especially if there are other species present, or as a side reaction. More accurately, hydrogen gas is evolved at the cathode. Therefore, the statement that oxygen gas is evolved at the cathode is *not* true.
D) It is used in aircraft industry. This is true. Anodizing is widely used in the aerospace industry to improve the corrosion resistance, wear resistance, and paint adhesion of aluminium alloys used in aircraft components.
The statement that is NOT true is C, specifically regarding oxygen evolution at the cathode.

– In anodizing, the metal article is the anode.
– Anodizing enhances corrosion resistance, wear resistance, and allows for dyeing.
– Hydrogen gas is typically evolved at the cathode during anodizing.

The electrolyte used in anodizing is typically an acidic solution (e.g., sulfuric acid, chromic acid, oxalic acid). The structure and properties of the anodic oxide layer depend on the type of electrolyte and process parameters. The porous nature of the oxide layer allows for subsequent dyeing if required.

39. Which one of the following is the correct order of pH for the given

Which one of the following is the correct order of pH for the given substances?

”Coffee

$). The pH scale is logarithmic, meaning a difference of 1 pH unit represents a tenfold difference in acidity or basicity. Body fluids like blood have specific pH ranges that must be maintained for proper physiological function.

40. Consider the following statements: While diluting concentrated nitric

Consider the following statements:
While diluting concentrated nitric acid solution

the concentration of [H₃O⁺] ions/ volume increases
water must be added slowly to concentrated acid
acid must be added slowly to water

Which of the statements given above is/are correct?

1, 2 and 3

1 and 2 only

3 only

2 and 3 only

This question was previously asked in

UPSC CDS-1 – 2023

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Let’s evaluate each statement:
1. the concentration of [H₃O⁺] ions/ volume increases: When diluting a concentrated acid by adding water, the *volume* of the solution increases significantly. While the total amount of H₃O⁺ ions might increase slightly due to more complete ionization in a more dilute solution, the increase in volume is much larger, leading to a *decrease* in the concentration of H₃O⁺ ions per unit volume. This statement is incorrect.
2. water must be added slowly to concentrated acid: Adding water to concentrated acid is a highly exothermic process. Adding water directly to concentrated acid can generate a large amount of heat rapidly, causing the water to boil and potentially splash corrosive acid out of the container. This is a dangerous procedure. This statement is incorrect.
3. acid must be added slowly to water: The correct and safe way to dilute concentrated acid is to add the concentrated acid slowly, drop by drop, to a large volume of water while stirring constantly. This method allows the heat generated by the exothermic reaction to be absorbed by the larger volume of water, preventing dangerous temperature increases and splashing. This statement is correct.
Based on the analysis, only statement 3 is correct.

– Dilution of concentrated acid is a highly exothermic process.
– Always add acid to water, not water to acid, for safety.
– Dilution decreases the concentration of hydronium ions.

The rule “Add Acid to Water, like A&W Root Beer” is a mnemonic to remember the correct dilution procedure. Stirring is important to ensure even distribution of heat and reactants. Wearing appropriate safety gear like goggles and gloves is essential when handling concentrated acids.