UPSC CDS-1 Archives

21. The Tropic of Cancer passes through how many coastal and landlocked St

The Tropic of Cancer passes through how many coastal and landlocked States of India, respectively?

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1 and 7

2 and 6

2 and 5

3 and 5

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The correct answer is B) 2 and 6. The Tropic of Cancer (23.5°N latitude) passes through eight states in India. These are Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura, and Mizoram. Among these:
– Coastal States: Gujarat and West Bengal (touching the sea).
– Landlocked States: Rajasthan (only a small southern tip), Madhya Pradesh, Chhattisgarh, Jharkhand, Tripura, and Mizoram.
Thus, the Tropic of Cancer passes through 2 coastal states and 6 landlocked states.

– The 8 states through which the Tropic of Cancer passes in India are Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura, and Mizoram.
– Coastal states are those with a coastline. Landlocked states are those completely surrounded by land or other states/countries.
– Gujarat has a long coastline on the Arabian Sea. West Bengal has a coastline on the Bay of Bengal. The other six states do not have a direct coastline on the Indian Ocean.

The Tropic of Cancer is an important imaginary line marking the northernmost latitude where the sun can be directly overhead. Its passage through these states influences their climate and geography.

22. According to the Census 2011, which of the following statements is/are

According to the Census 2011, which of the following statements is/are correct?

1. A person who can only read but cannot write, is not literate.
2. A person aged seven years and above, who can both read and write with understanding in any language is treated as literate.

Select the correct answer using the code given below.

1 only

2 only

Both 1 and 2

Neither 1 nor 2

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The correct answer is C) Both 1 and 2. According to the Census 2011 definition, a person is considered literate if they are aged seven years and above and can both read and write with understanding in any language. Statement 2 is the direct definition. Statement 1 is a logical consequence of this definition: if someone can only read but not write, they do not meet the criteria of being able to “both read and write,” and are therefore not counted as literate.

– The Census 2011 defines a literate person as someone aged 7 years and above who can read and write with understanding in any language.
– A person who can merely read but cannot write is not considered literate by this definition.
– Children below 7 years are considered illiterate by definition, irrespective of their ability to read or write.

The literacy rate in India as per Census 2011 is approximately 74.04%. This definition has been used in Indian censuses since 1991. Prior to 1991, the criteria was being able to read and write with understanding in any language for persons aged 5 years and above.

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23. Rani told her friends that last year she did boating in four different

Rani told her friends that last year she did boating in four different lakes, namely, Loktak, Barapani, Kolleru and Pulicat. Which of the following States did she visit?

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Manipur, Meghalaya, Kerala, Tamil Nadu

Manipur, Meghalaya, Andhra Pradesh, Tamil Nadu

Mizoram, Assam, Kerala, Tamil Nadu

Mizoram, Assam, Andhra Pradesh, Tamil Nadu

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The correct answer is B) Manipur, Meghalaya, Andhra Pradesh, Tamil Nadu. The lakes mentioned are located in the following states: Loktak Lake in Manipur, Barapani Lake (Umiam Lake) in Meghalaya, Kolleru Lake in Andhra Pradesh, and Pulicat Lake in Andhra Pradesh and Tamil Nadu. Therefore, the states visited are Manipur, Meghalaya, Andhra Pradesh, and Tamil Nadu.

– Loktak Lake is the largest freshwater lake in North East India, famous for the floating phumdis, located in Manipur.
– Barapani Lake, also known as Umiam Lake, is a reservoir in Meghalaya.
– Kolleru Lake is one of the largest freshwater lakes in India, located between the Krishna and Godavari deltas in Andhra Pradesh.
– Pulicat Lake is the second largest brackish water lagoon in India, situated on the border of Andhra Pradesh and Tamil Nadu (mostly in Andhra Pradesh).

Knowing the locations of major lakes and geographical features is important for general knowledge and geography sections of competitive exams. The states listed in other options do not correspond correctly to the locations of all four lakes.

24. Which of the following sets of States shares boundary with Telangana?

Which of the following sets of States shares boundary with Telangana?

Odisha, Andhra Pradesh, Karnataka, Maharashtra

Chhattisgarh, Andhra Pradesh, Karnataka, Madhya Pradesh

Odisha, Andhra Pradesh, Karnataka, Madhya Pradesh

Chhattisgarh, Andhra Pradesh, Karnataka, Maharashtra

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The correct answer is D) Chhattisgarh, Andhra Pradesh, Karnataka, Maharashtra. All the states listed in this set share a boundary with Telangana. Telangana shares borders with Maharashtra, Chhattisgarh, Odisha, Andhra Pradesh, and Karnataka. Option D lists four of these five neighbours.

– Telangana was formed in 2014 by bifurcating Andhra Pradesh.
– Its neighbouring states are Maharashtra (North/North-West), Chhattisgarh (North/North-East), Odisha (North-East – a small border), Andhra Pradesh (East/South), and Karnataka (South/West).
– Option A (Odisha, Andhra Pradesh, Karnataka, Maharashtra) also lists states that all border Telangana. However, typically, in MCQs, there is only one correct answer. Given the options, both A and D contain sets where every listed state shares a boundary with Telangana. Assuming the question expects one specific set from the choices, and without further clarification or context that would differentiate A and D, both appear geographically correct. However, option D lists states covering borders in multiple directions (North, East, South, West). In some contexts, D might be preferred for including Chhattisgarh which has a longer border with Telangana than Odisha’s small border.
– Option B and C are incorrect as they include Madhya Pradesh, which does not share a boundary with Telangana.

The question phrasing “Which of the following sets of States shares boundary with Telangana?” implies that all states within the chosen set must share a boundary with Telangana. Both set A and set D satisfy this condition. However, in a single-choice question context, D is chosen assuming it’s the intended answer, potentially due to a slightly more prominent set of neighbours included or a flaw in the question/options design allowing for two correct answers under a strict interpretation.

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25. Consider the following clues about a State of India: It is known as

Consider the following clues about a State of India:

It is known as ‘land of red river and blue hills’.
It contains three of the six physiographic divisions of India.
It covers about 2.39 percent of total area of the country.

Identify the State on the basis of the given clues.

Karnataka

Andhra Pradesh

Assam

Chhattisgarh

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The correct answer is C) Assam. The clues accurately describe the State of Assam: it is known as the ‘land of red river and blue hills’ (referring to the Brahmaputra and the surrounding hills), it encompasses parts of the Northern Mountains, Northern Plains (Brahmaputra Valley), and the Peninsular Plateau (Karbi Anglong/Meghalaya Plateau extension), and its area (approx. 78,438 sq km) constitutes about 2.39% of India’s total area (approx. 3.287 million sq km).

– ‘Land of red river and blue hills’ is a popular epithet for Assam, referencing the Brahmaputra river and the Eastern Himalayas and hills.
– India’s major physiographic divisions include the Northern Mountains, Northern Plains, Peninsular Plateau, Coastal Plains, Islands, and the Great Indian Desert. Assam has portions of the first three.
– Area calculation: (Area of State / Total Area of India) * 100. For Assam, (78438 / 3287263) * 100 ≈ 2.386%.

Karnataka, Andhra Pradesh, and Chhattisgarh are significant states but do not match all three clues, particularly the ‘red river and blue hills’ description and the area percentage. Karnataka is known for the Western Ghats and Plateau region. Andhra Pradesh is primarily known for its coastal plains and Eastern Ghats. Chhattisgarh is part of the Peninsular Plateau region.

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26. Which one of the following is not an oxidation reaction?

Which one of the following is not an oxidation reaction?

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Rusting of iron

Opening of soda bottle

Rancidity

Combustion

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The correct answer is B) Opening of soda bottle. This is a physical process involving the release of dissolved carbon dioxide gas due to reduced pressure upon opening the bottle. It does not involve a chemical reaction where a substance loses electrons or gains oxygen (oxidation).

– Oxidation is a chemical process involving the loss of electrons or an increase in oxidation state by a molecule, atom, or ion. It often involves reaction with oxygen.
– Rusting of iron is the oxidation of iron in the presence of oxygen and moisture to form iron oxides (rust).
– Rancidity is the oxidation or hydrolysis of fats and oils, leading to unpleasant smells and flavors.
– Combustion is a chemical process (often rapid) between a substance and an oxidant, usually oxygen, to produce heat and light. It is typically an oxidation-reduction (redox) reaction.

While opening a soda bottle involves a release of energy (due to decreasing potential energy of the compressed gas), the fundamental process is a physical change of state and solubility due to pressure change, not a chemical oxidation reaction like rusting, rancidity, or combustion.

27. Which of the following statements with regard to heating of lead nitra

Which of the following statements with regard to heating of lead nitrate powder over a flame are correct?

Brown fumes of NO are released.
Colourless O₂ gas is released.
It is an example of oxidation reaction.
It is an example of thermal decomposition used for the production of NO₂ gas.

Select the correct answer using the code given below.

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1 and 2

2, 3 and 4

1, 3 and 4

2 and 4 only

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Heating lead(II) nitrate powder is a classic example of thermal decomposition. The reaction is: 2Pb(NO₃)₂(s) → 2PbO(s) + 4NO₂(g) + O₂(g).
Statement 1: Brown fumes of NO are released. Incorrect. The brown fumes are due to nitrogen dioxide (NO₂), not nitrogen monoxide (NO), which is colourless.
Statement 2: Colourless O₂ gas is released. Correct. Oxygen gas is a product of the decomposition and is colourless.
Statement 3: It is an example of oxidation reaction. Correct. While it’s a redox reaction involving both oxidation and reduction (Nitrogen is reduced from +5 to +4 in NO₂, and Oxygen is oxidized from -2 in NO₃⁻ to 0 in O₂), it is valid to say that it is *an example* of a reaction where oxidation occurs.
Statement 4: It is an example of thermal decomposition used for the production of NO₂ gas. Correct. Heating breaks down lead nitrate, and NO₂ is one of the products, making it a method for producing NO₂.
Statements 2, 3, and 4 are correct, while statement 1 is incorrect.

Thermal decomposition of lead nitrate produces solid lead oxide, brown nitrogen dioxide gas, and colourless oxygen gas. It is a redox reaction.

Metal nitrates decompose on heating, but the products vary depending on the reactivity of the metal. Nitrates of less reactive metals like lead and copper produce metal oxide, nitrogen dioxide, and oxygen. Nitrates of more reactive metals like sodium and potassium usually produce metal nitrite and oxygen.

28. Which of the following statements with regard to the reaction given be

Which of the following statements with regard to the reaction given below are correct? CaO(s) + H₂O(l) → Ca(OH)₂(aq) + Heat

1. Quicklime is used for white-washing of walls.
2. The solution of slaked lime is used for whitewashing of walls.
3. CaO reacts slowly with CO₂ in air to form a thin layer of CaCO₃ on walls.
4. Calcium hydroxide called ‘slaked lime’ is an inorganic compound.

Select the correct answer using the code given below.

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1 and 4 only

2 and 4

2 and 3

1, 3 and 4

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The reaction given is CaO(s) + H₂O(l) → Ca(OH)₂(aq) + Heat. This is the slaking of quicklime (CaO) to produce slaked lime (Ca(OH)₂).
Statement 1: Quicklime (CaO) is used for white-washing of walls. While quicklime is the starting material, it is typically slaked with water to form calcium hydroxide (slaked lime) before being applied for whitewashing. So, this statement is not strictly accurate as CaO itself is not directly applied.
Statement 2: The solution of slaked lime (Ca(OH)₂) is used for whitewashing of walls. Correct. A suspension or solution of calcium hydroxide (slaked lime) is the material commonly applied as whitewash.
Statement 3: CaO reacts slowly with CO₂ in air to form a thin layer of CaCO₃ on walls. Incorrect. It is calcium hydroxide (slaked lime, Ca(OH)₂) that reacts with carbon dioxide in the air over time to form calcium carbonate (CaCO₃), which hardens and gives a shiny finish to the whitewash. CaO itself reacts readily with CO₂, but the reaction relevant to the setting of whitewash is between Ca(OH)₂ and CO₂.
Statement 4: Calcium hydroxide called ‘slaked lime’ is an inorganic compound. Correct. Calcium hydroxide is a compound of calcium, oxygen, and hydrogen, without carbon-hydrogen bonds, classifying it as an inorganic compound.
Based on the analysis, statements 2 and 4 are correct, and statements 1 and 3 are incorrect or less accurate.

Slaked lime (Ca(OH)₂) solution is used for whitewashing. Slaked lime reacts with CO₂ in air to form CaCO₃.

The process of whitewashing involves applying slaked lime (calcium hydroxide) to walls. The applied calcium hydroxide then reacts slowly with atmospheric carbon dioxide to form a hard layer of calcium carbonate, which is durable and provides a good white finish. CaO is also known as quicklime or burnt lime, and Ca(OH)₂ is also known as hydrated lime or slaked lime.

29. Consider the following statements regarding burning of magnesium ribbo

Consider the following statements regarding burning of magnesium ribbon in air :

1. White powder of MgO is formed.
2. It is an example of combustion reaction.
3. Heat and light are produced.

Which of the statements given above are correct?

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1 and 2 only

1 and 3 only

2 and 3 only

1, 2 and 3

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When magnesium ribbon is burned in air, it reacts vigorously with oxygen to form magnesium oxide (MgO). The balanced chemical equation is 2Mg(s) + O₂(g) → 2MgO(s). This reaction produces a bright white light and considerable heat.
Statement 1: White powder of MgO is formed. Correct, magnesium oxide is a white solid.
Statement 2: It is an example of combustion reaction. Correct, combustion is a rapid reaction between a substance and an oxidant, usually oxygen, to produce heat and light.
Statement 3: Heat and light are produced. Correct, the burning of magnesium is highly exothermic and produces a characteristic bright white flame.
All three statements are correct.

Burning of magnesium is a combustion reaction producing magnesium oxide, heat, and light.

Magnesium also reacts with nitrogen in the air during burning, forming a small amount of magnesium nitride (Mg₃N₂), but the primary product with oxygen is MgO. Magnesium is used in fireworks and flares due to the intense light it produces when burning.

30. The power of a lens of focal length 10 cm is

The power of a lens of focal length 10 cm is

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0⋅1 dioptre

1 dioptre

10 dioptre

100 dioptre

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The power (P) of a lens is defined as the reciprocal of its focal length (f). The focal length must be expressed in meters for the power to be in dioptres (D).
Given focal length f = 10 cm.
Convert focal length to meters: f = 10 cm / 100 cm/m = 0.1 meters.
Power P = 1 / f (in meters) = 1 / 0.1 m = 10 dioptres.

Power of a lens (in dioptres) = 1 / Focal length (in meters).

A convex lens has a positive focal length and positive power, indicating that it converges light rays. A concave lens has a negative focal length and negative power, indicating that it diverges light rays. The unit dioptre is defined as m⁻¹.