UGC NET Questions (Paper – 1)

Statements A, B, D and E are correct and consistent with basic climate science. Statement A correctly lists major anthropogenic greenhouse gases, statement B explains how they trap outgoing long-wave radiation, statement D points to human-induced enhancement of global warming and statement E recognises the protective role of stratospheric ozone. Statement C is incorrect because the natural greenhouse effect is essential for maintaining Earth’s mean temperature at a habitable level. Therefore, the only combination that includes all true statements while excluding the false one is A, B, D and E.

Option A:
Option A is incorrect because it includes A, B and D but omits E. While A, B and D are indeed correct statements, E is also correct as stratospheric ozone shields living organisms from harmful ultraviolet radiation. By leaving out a true statement, this option does not fully capture the set of correct statements.

Option B:
Option B is correct because it includes statements A, B, D and E, all of which are scientifically accurate. It excludes statement C, which falsely portrays the greenhouse effect as entirely harmful and ignores its natural role in maintaining habitable temperatures. Hence, this option represents the complete and precise set of correct statements asked for in the question.

Option C:
Option C is incorrect because it adds statement C to the set of otherwise correct statements A, B and D. Statement C is wrong since the greenhouse effect in its natural form is beneficial and only its anthropogenic enhancement is problematic. Including a false statement makes this combination unacceptable.

Option D:
Option D is incorrect because it combines B, C, D and E. Although B, D and E are correct, the presence of statement C, which misrepresents the greenhouse effect as wholly harmful, makes the entire combination wrong. A valid answer must exclude all incorrect statements.

The Paris Agreement specifies the long term goal of holding the increase in global average temperature to well below 2 degrees Celsius above pre industrial levels and to pursue efforts to limit the temperature increase to 1.5 degrees. The stem explicitly uses the phrase “well below” and then mentions pursuing efforts for 1.5 degrees,which confirms that the blank should be 2. Therefore Option C is the correct choice.

Option A:
A target of 1 degree is not the stated “well below” threshold in the Paris Agreement and does not appear as the main temperature limit in its text.

Option B:
1.5 degrees is included in the Paris Agreement as an aspirational effort goal (“pursuing efforts to limit to 1.5”),but it is not the number that follows “well below” in the main clause.

Option C:
The 2 degree figure is the key reference point in the Paris Agreement: parties agreed to keep warming well below 2°C and pursue efforts toward 1.5°C. This matches the stem exactly.

Option D:
4 degrees is far above agreed limits and is associated with dangerous warming scenarios,not the Paris temperature goal.

Global warming is driven largely by enhanced greenhouse gas concentrations that trap heat, altering climate patterns. Ozone depletion, on the other hand, involves breakdown of ozone molecules in the stratosphere by chlorine and bromine released from substances such as CFCs and halons. While the two issues interact in complex ways, they are scientifically distinct problems with different primary causes, effects and treaties.

Option A:
Option A is incorrect because global warming and ozone depletion are not identical; conflating them leads to conceptual confusion and wrong policy responses.

Option B:
Option B is correct as it clearly separates the temperature-related phenomenon linked to greenhouse gases from the UV-shielding issue linked to ozone chemistry and CFCs.

Option C:
Option C is incorrect; volcanic eruptions and earthquakes are not the sole or main causes of these global environmental changes.

Option D:
Option D is incorrect because ozone depletion actually increases, not reduces, UV-B reaching the surface.

Statements A, B and D are correct because they describe well-known impacts of global warming on coasts, agriculture, water and cryosphere. However, statement C is incorrect as research indicates that global warming can influence the frequency and intensity of certain extreme weather events such as heatwaves and heavy rainfall. Since option B treats C as correct along with the other statements, it cannot logically be the correct answer. The correct combination must therefore include only A, B and D, excluding C.

Option A:
Option A is correct because it gathers together A, B and D, all of which are supported by climate science, while omitting C. It recognises coastal risks, shifts in agriculture and water stress and the implications of glacier melt. By excluding the wrong statement, it matches the question requirement.

Option B:
Option B is incorrect as it treats all four statements as correct. It incorrectly endorses C, which denies any influence of global warming on extreme events, contradicting current scientific assessments. Consequently, this option is invalid.

Option C:
Option C is incorrect because it includes C alongside B and D and leaves out A. Apart from omitting a correct statement about sea-level rise, it wrongly accepts C, thereby misrepresenting the climate change–extreme weather link.

Option D:
Option D is incorrect as it includes A, C and D and omits B. It still retains the false statement C and thus fails to present an accurate set of correct statements about global warming impacts.

The greenhouse effect occurs when gases such as carbon dioxide,water vapour and methane absorb outgoing infrared radiation and re emit it toward the Earth’s surface. This process keeps the planet’s average temperature at a level suitable for life. The stem clearly describes this trapping and warming mechanism. Therefore the correct name is greenhouse effect.

Option A:
The albedo effect refers to the reflectivity of Earth’s surface and atmosphere,which determines how much solar radiation is reflected back into space. While it influences climate,it is distinct from the trapping of long wave radiation described in the question.

Option B:
The greenhouse effect involves the selective absorption and re emission of infrared radiation by greenhouse gases. This natural effect becomes enhanced when human activities increase greenhouse gas concentrations. Because the question focuses on this trapping process,greenhouse effect is the appropriate term.

Option C:
Ozone depletion is the thinning of the stratospheric ozone layer primarily due to chlorofluorocarbons. It increases the amount of harmful ultraviolet radiation reaching Earth,but it is not about trapping heat. Hence it is not the correct option.

Option D:
Acid rain describes precipitation with elevated acidity caused mainly by sulphur dioxide and nitrogen oxides dissolving in water. It leads to ecosystem damage and material corrosion but does not directly refer to atmospheric heat trapping.

Global warming is conventionally defined as the rise in the average temperature of the Earth’s surface air and oceans over decades. This increase is driven primarily by human induced greenhouse gas emissions. The stem clearly points to a long term increase in average temperature,so “surface” is the correct qualifier. It aligns with how global warming is measured and discussed in climate science.

Option A:
The core refers to the innermost part of the Earth and its temperature changes do not capture climate trends experienced by living organisms. Global warming discussions rarely focus on core temperature,so Option A is inaccurate.

Option B:
Surface temperature records from land and sea provide the key empirical basis for assessing global warming. These datasets show a clear upward trend over the last century. This is precisely the aspect highlighted in the stem.

Option C:
The crust describes the solid outer shell of the Earth and its temperature is uneven and not used as the primary climate indicator. Thus Option C does not match the standard definition of global warming.

Option D:
The mantle is a deep interior layer and its thermal behaviour is largely independent of atmospheric greenhouse gas levels. It is not the focus of climate change discussions,so Option D is not appropriate.

Carbon dioxide is the primary greenhouse gas emitted by human activities,especially from burning fossil fuels for electricity,transport and industry. Its long atmospheric lifetime and high volume make it the dominant driver of anthropogenic climate change. The stem explicitly links the gas to combustion of coal,oil and natural gas,which clearly points to carbon dioxide. Hence Option A is correct.

Option A:
Carbon dioxide concentrations have been rising steadily since the industrial revolution,enhancing the greenhouse effect. Because of this central role,international climate agreements focus heavily on reducing CO₂ emissions. This explanation fits the description in the question.

Option B:
Methane is also a potent greenhouse gas and arises from agriculture,fossil fuel extraction and waste,but its global emissions from burning fossil fuels are smaller in volume than CO₂. It is therefore not the most significant gas in the specific context described.

Option C:
Ozone acts as a greenhouse gas in the troposphere but is not emitted directly in large amounts from fossil fuel combustion. It is mainly formed as a secondary pollutant,so it does not match the stem as closely as carbon dioxide.

Option D:
Carbon monoxide is a toxic gas produced by incomplete combustion and has health impacts,but its direct greenhouse effect is relatively weak compared to CO₂. Thus it is not the best answer here.

Carbon dioxide is the most significant anthropogenic greenhouse gas in terms of total emissions. It is released in large quantities through burning coal,oil and natural gas and through deforestation. Its long atmospheric lifetime and high volume make it the main driver of human induced climate change. Therefore carbon dioxide best fits the description in the question.

Option A:
Oxygen is a major component of the atmosphere but it is not a greenhouse gas. It does not trap outgoing infrared radiation in the way greenhouse gases do. Hence it cannot be the primary greenhouse gas mentioned in the stem.

Option B:
Nitrogen makes up the largest fraction of Earth’s atmosphere. However it is largely inert and does not act as a greenhouse gas in its diatomic form. Therefore it is not responsible for the described warming effect.

Option C:
Ozone in the troposphere acts as a greenhouse gas and pollutant,but its concentration is much lower than that of carbon dioxide. It is important locally but is not the primary anthropogenic greenhouse gas globally. Thus it is not the best answer here.

Option D:
Carbon dioxide is produced by combustion processes in power plants,industry and transport as well as by land use changes. It accumulates in the atmosphere and enhances the greenhouse effect. This makes it the central gas referred to in the question.

The natural greenhouse effect keeps Earth warm enough for life by trapping some outgoing infrared radiation. Human activities such as burning fossil fuels and deforestation have increased greenhouse gas levels,leading to extra warming beyond this natural level. This extra warming is known as the enhanced greenhouse effect. Therefore enhanced is the correct word to complete the phrase in the stem.

Option A:
The natural greenhouse effect refers to the baseline warming that has always existed due to naturally occurring greenhouse gases. It is essential for maintaining habitable temperatures and is not the additional human induced component highlighted in the question.

Option B:
Moderate does not correspond to any widely recognised term in climate science. While the enhanced greenhouse effect may or may not be moderate, the established term focuses on the idea of being stronger than the natural effect,not moderate.

Option C:
Shielded greenhouse effect is not an accepted expression. Shielding would imply blocking radiation rather than trapping more of it. Thus this option does not fit the phenomenon described in the stem.

Option D:
Enhanced greenhouse effect clearly indicates that the original process has been intensified by human actions. It accounts for the observed trend of rising global temperatures and changing climate patterns,exactly what the question refers to.

The IPCC is a scientific body established by the UN to provide policymakers with regular assessments of the science of climate change. It reviews and synthesises thousands of research studies on physical science, impacts, adaptation and mitigation. Its comprehensive assessment reports inform international negotiations and national policy but do not themselves set rules. Thus, the primary role of assessing and reporting on climate knowledge, as described in option C, is accurate.

Option A:
Option A is incorrect because treaty negotiation and adoption are functions of political bodies like the Conference of the Parties to the UNFCCC, not of the IPCC. The panel supplies information but does not make binding legal decisions.

Option B:
Option B is incorrect since financing renewable energy projects is handled by entities such as the Green Climate Fund and development banks. The IPCC does not manage project funding.

Option C:
Option C is correct as it emphasises the assessment and reporting role. By summarising peer-reviewed science in an accessible way, the IPCC helps bridge the gap between researchers and policymakers without advocating specific policies.

Option D:
Option D is incorrect because enforcing penalties on countries is not within the IPCC’s mandate. Compliance and enforcement issues are addressed within international agreements and national laws.

The Intergovernmental Panel on Climate Change is a scientific body established by UNEP and WMO to provide comprehensive assessments of climate change. It synthesises peer reviewed research on the physical science basis,impacts and response strategies. Its reports inform international negotiations and national policies. Thus the description in the question clearly points to the IPCC.

Option A:
UNEP,the United Nations Environment Programme,coordinates environmental activities within the UN system and assists developing countries. While it supports IPCC work,it is not itself the scientific assessment panel described in the stem. Therefore it is not the correct answer.

Option B:
UNDP,the United Nations Development Programme,focuses on development issues such as poverty reduction,governance and resilience. It uses climate information but does not produce global scientific assessments of climate change. Hence it does not match the concept in the question.

Option C:
UNFCCC,the United Nations Framework Convention on Climate Change,is the international treaty that provides the political framework for climate negotiations. It relies on IPCC assessments for scientific guidance but is not the assessment body itself. Therefore it is not the right option here.

Option D:
The Intergovernmental Panel on Climate Change regularly publishes assessment reports,special reports and methodology guidelines. By evaluating existing scientific literature,it offers authoritative syntheses rather than conducting original research. This role matches exactly what the question describes.