Greenhouse Gases and Atmosphere

Oxygen was largely absent in Earth's early atmosphere. With the evolution of photosynthetic plants (and earlier cyanobacteria), oxygen began accumulating as a byproduct of photosynthesis. This 'Great Oxygenation Event' dramatically changed Earth's atmosphere. Option D correctly identifies oxygen as the new gas.

CO2 is a primary greenhouse gas that absorbs and re-emits infrared radiation. Unlike O2 and N2 which are transparent to infrared, CO2's molecular structure allows it to trap heat.

Photosynthesis is the primary biological process that produces oxygen as a byproduct when plants, algae, and cyanobacteria convert CO2 and water into glucose. Combustion consumes oxygen, hydrolysis breaks molecules using water, and ammonification produces ammonia - none release oxygen into the atmosphere.

Combustion of fossil fuels and biomass releases carbon dioxide into the atmosphere. Fossilization removes carbon from the cycle, while nitrification and ammonification are parts of the nitrogen cycle.

Yes. nitrogen constitutes 78.08% of the atmospheric air.

This is largely responsible for the green house effect.The volume of other gases is constant but the volume of carbon dioxide has been rising in the past few decades mainly because of the burning of fossil fuels. This has also increased the temperature of the air.

Carbon dioxide is the primary greenhouse gas responsible for global warming. It is released through human activities like burning fossil fuels, deforestation, and industrial processes. CO2 traps heat in the atmosphere, causing the greenhouse effect and leading to global climate change. Noble gases like Helium, Argon, and Xenon are inert and do not contribute to warming.

Nitrogen (N2) is not a greenhouse gas because its molecular structure is symmetrical and non-polar, so it does not absorb infrared radiation. The other options - carbon dioxide, sulphur dioxide, and ethane - all have molecular structures that trap heat in the atmosphere, contributing to the greenhouse effect.

Global warming is the process of increase in earth's temperature due to an increase in air pollution. One of the major gases responsible for pollution is CO₂. Burning fossil fuels results in huge emissions of CO₂, which causes global warming.

Paddy fields produce methane through anaerobic decomposition of organic matter in flooded soil conditions. Methanogenic archaea break down organic material in the oxygen-depleted environment, releasing methane (CH4) which is a potent greenhouse gas connected with global warming. While CO2 is also a greenhouse gas, paddy fields are specifically noted for methane emissions.

1, 2 and 4 only

Yes, it is the correct answer. Carbon dioxide, sulphur dioxide and methane are responsible for the greenhouse effect.

Carbon dioxide (CO2) is the primary greenhouse gas responsible for global warming, contributing about 76% of all greenhouse gas emissions from human activities. While CFCs are also greenhouse gases with high global warming potential, CO2 is by far the major one in terms of total emissions and overall impact.

Ozone (O3) has a dual nature - it is beneficial in the stratosphere where it forms the ozone layer that protects life from harmful UV radiation, but harmful at ground level where it is a toxic pollutant and component of smog. This Jekyll-and-Hyde character makes ozone unique among atmospheric gases. Oxygen is essential for life but not harmful in normal concentrations. Carbon dioxide and methane are primarily known as greenhouse gases without significant protective roles.

All three statements are consistent with WMO data from 2006. Statement I correctly notes greenhouse gases reached record levels with CO2 being the primary driver. Statement II accurately states CO2 and N2O concentrations were at recorded highs. Statement III is also correct as methane levels remained relatively stable between 2005 and 2006, unlike the other two gases which showed significant increases.