21. Which one of the following air pollutants combines with the haemoglobi

Which one of the following air pollutants combines with the haemoglobin of human blood and reduces its oxygen-carrying capacity, leading to suffocation and may cause even death?

Chlorofluorocarbon
Fly ash
Carbon monoxide
Sulphur dioxide
This question was previously asked in
UPSC CDS-2 – 2016
Carbon monoxide (CO) is a toxic gas that readily binds to haemoglobin in red blood cells, forming carboxyhaemoglobin (COHb). This binding affinity is much higher than that of oxygen.
The formation of carboxyhaemoglobin reduces the amount of haemoglobin available to transport oxygen from the lungs to the body’s tissues. This leads to oxygen deprivation, causing symptoms like headache, dizziness, nausea, and in severe cases, suffocation and death. Other listed pollutants do not primarily affect oxygen transport in this manner. Chlorofluorocarbons (CFCs) damage the ozone layer. Fly ash is particulate matter from combustion. Sulphur dioxide (SO₂) is a respiratory irritant and contributor to acid rain.
Carbon monoxide is produced from the incomplete combustion of carbon-containing fuels (e.g., in vehicles, furnaces, stoves). Because it is odourless, colourless, and tasteless, it is often called the “silent killer”.

22. The HIV virus weakens the immunity of a person because it destroys

The HIV virus weakens the immunity of a person because it destroys

mast cells
platelets
erythrocytes
lymphocytes
This question was previously asked in
UPSC CDS-2 – 2016
The HIV virus weakens the immunity of a person because it destroys lymphocytes.
HIV primarily targets and infects CD4+ T lymphocytes (also known as T helper cells), which are critical components of the adaptive immune system. The virus replicates within these cells and eventually destroys them.
Progressive destruction of CD4+ T cells leads to a severe decline in immune function, making individuals susceptible to opportunistic infections and certain cancers that a healthy immune system would normally fight off. This advanced stage of HIV infection is known as Acquired Immunodeficiency Syndrome (AIDS).

23. Which one of the following is the largest source of electricity in

Which one of the following is the largest source of electricity in India?

Hydropower plants
Nuclear power plants
Thermal power plants
Wind energy
This question was previously asked in
UPSC CDS-2 – 2016
Thermal power plants are the largest source of electricity in India.
India’s electricity generation mix is dominated by thermal power, primarily coal-based power plants. Although renewable energy sources (like wind and solar) are rapidly growing, and hydro and nuclear power contribute, thermal power accounts for the largest share of total installed capacity and actual generation.
As of recent data, thermal power (including coal, gas, and diesel) constitutes over 50% of India’s total installed electricity generation capacity, and its contribution to actual generation is even higher due to higher capacity utilization compared to some renewable sources.

24. Which one of the following is most sensitive to environmental change?

Which one of the following is most sensitive to environmental change?

Amphibian
Reptile
Mammal
Insect
This question was previously asked in
UPSC CDS-2 – 2016
Amphibians are generally considered most sensitive to environmental change among the given options.
Amphibians are particularly vulnerable to environmental changes due to several factors: their permeable skin readily absorbs substances from the environment (water and air), they often rely on both aquatic and terrestrial habitats during their life cycle, and many have specific requirements for reproduction and development. These characteristics make them highly susceptible to changes in water quality, habitat destruction, pollution, and climate change, serving as important bioindicators.
While reptiles, mammals, and insects are also affected by environmental changes, amphibians’ unique physiological and life-cycle traits often make them among the first groups to show negative impacts from habitat degradation and pollution.

25. Which one of the following gases is released mostly from landfills in

Which one of the following gases is released mostly from landfills in urban areas?

Nitrogen
Hydrogen
Methane
Oxygen
This question was previously asked in
UPSC CDS-2 – 2016
Methane is the gas released mostly from landfills in urban areas.
Landfills are significant sources of landfill gas, which is produced by the anaerobic decomposition of organic solid waste. The primary components of landfill gas are methane (CH4) and carbon dioxide (CO2). While CO2 is also released, methane is often present in high concentrations (typically 40-60%) and is a potent greenhouse gas.
Landfill gas collection systems are often installed in large landfills to capture methane for energy generation or flaring to reduce its release into the atmosphere. Other gases like nitrogen, oxygen, and hydrogen might be present in trace amounts, but methane and carbon dioxide constitute the bulk of the gas produced.

26. Which among the following is not a condition for the disqualificatio

Which among the following is not a condition for the disqualification of a Member of Parliament?

Voluntary acquisition of citizenship of a foreign country
Holding the office of the Chairperson of the National Commission for Women
The Member abstains from voting in the House without prior permission
The Member holds the office of the Chairman of the Board of Directors of the National Coal Development Corporation Ltd.
This question was previously asked in
UPSC CDS-2 – 2021

Disqualification of a Member of Parliament can occur on several grounds listed in the Constitution (Article 102) and the Representation of the People Act, 1951, including voluntarily acquiring foreign citizenship (A) and holding an office of profit under the government (B and D could potentially be offices of profit depending on their specific nature and whether they are exempted by law). Abstaining from voting in the House *without prior permission* is relevant to disqualification under the Tenth Schedule (Anti-Defection Law), but the strict condition is voting or abstaining contrary to any direction (whip) issued by the political party, *unless* such vote or abstention is condoned by the party within fifteen days. Merely abstaining without permission, without violating a whip, is not a ground for disqualification. Thus, the phrasing in C is not an independent, always applicable condition for disqualification.

While violating a party whip by abstaining *can* lead to disqualification under the anti-defection law, simply abstaining without permission is not a direct, universally applicable ground without reference to a whip or other rules. Acquisition of foreign citizenship (A) and holding certain offices (like potential offices of profit in B and D) are more direct grounds unless exempted.

Office of Profit is a complex concept; holding a position is disqualifying if it is considered an office of profit under the government and is not exempted by Parliament. Acquiring foreign citizenship automatically leads to cessation of Indian citizenship and thus disqualification. Defection grounds relate to changing parties or violating party directives/whips on voting/abstention.

27. Which one of the following statements about the All India Services is

Which one of the following statements about the All India Services is correct?

The All India Services may be created by an Act of the Parliament.
The endorsement of the Rajya Sabha is not essential for the creation of the All India Services.
The rules of recruitment to the All India Services are determined by the UPSC.
The conditions of service to the All India Services may be altered by the UPSC.
This question was previously asked in
UPSC CDS-2 – 2017
Statement A is correct. Article 312 of the Constitution of India provides for the creation of All India Services common to the Union and the States. It states that if the Rajya Sabha has declared by a resolution supported by not less than two-thirds of the members present and voting that it is necessary or expedient in the national interest so to do, Parliament may by law provide for the creation of one or more All India Services. Thus, Parliament can create AIS by an Act, but it requires a specific resolution from the Rajya Sabha.
The creation of All India Services requires a specific procedure involving a Rajya Sabha resolution followed by an Act of Parliament.
Statement B is incorrect because the endorsement (resolution) of the Rajya Sabha is essential for the creation of new All India Services under Article 312. Statement C is incorrect; the rules of recruitment and conditions of service are determined by the Central Government in consultation with the State Governments, not solely by the UPSC. The UPSC conducts the recruitment examinations. Statement D is incorrect; conditions of service are determined by the Central Government and cannot be altered by the UPSC.