Consider the following statements : Statement I : Studies indicate that carbon dioxide emissions from cement industry account for more than 5% of global carbon emissions. Statement II : Silica-bearing clay is mixed with limestone while manufacturing cement. Statement III : Limestone is converted into lime during clinker production for cement manufacturing. Which one of the following is correct in respect of the above statements?

Gives an explicit example of a sectoral share (global deforestation ≈ 20% of world's CO2 emissions), illustrating that individual activities/sectors can be expressed as significant percentages of total emissions.

A student could use this sector-share framing and compare published cement-sector CO2 tonnage (from external sources) to global CO2 totals to judge whether cement exceeds 5%.

Provides national and global-emissions percentage context (India's annual emissions ≈ 7% of global emissions), showing that percentages of global emissions are a standard and meaningful way to present contribution.

Use this example of reporting (national % of global) to understand and evaluate claims about a single industry's % share (cement) by comparing industry totals to global totals.

States that CO2 emissions come from a variety of human activities and that human-related emissions have driven atmospheric increases — implying emissions inventories are disaggregated by source.

Recognize that cement is one identifiable human activity in emissions inventories; a student could consult such inventories (sector breakdowns) to see whether cement's share exceeds 5%.

Gives an example of attributing a percentage of a pollutant (black carbon) to particular countries (15–35% from China and India), showing that attributing portions of global pollutants to specific sources/regions is common and feasible.

Use the same approach to attribute CO2: combine known cement-industry emissions by country/region with global CO2 totals to estimate the industry's global percentage.

Notes the significant historical increase in atmospheric CO2 due to human activity, indicating the importance of quantifying sources and their relative contributions over time.

A student could use historical/global CO2 totals as the denominator and compare cement-sector emission time series (numerator) to assess whether the sector's share is above 5%.

Gives the chemical rule that heating calcium carbonate (limestone) causes thermal decomposition to calcium oxide and CO2—a direct mineral-origin CO2 source used in cement manufacture.

A student can combine this reaction with the fact that limestone is a main cement feedstock to infer that calcining large amounts of limestone will release CO2 from the rock itself.

States that some industrial processes (explicitly including cement production) emit CO2 via chemical reactions not involving combustion.

One can use this general rule to deduce that CO2 from mineral reactions (like calcination) is a recognized emission source in the cement sector, separate from fuel combustion.

Describes limestone composition as largely calcium carbonate but also containing silica, alumina and other oxides—the same components mixed/used in cement raw mix.

A student could link the presence of carbonate in limestone to the decomposition reaction (snippet 9) and note that clay/silica supply non-carbonate components needed for clinker formation, helping separate where CO2 originates.

Provides evidence of the very large scale of limestone production for cement (massive increases in tonnage used as raw material).

Combining the large scale of limestone use with the decomposition rule suggests that mineral-source CO2 from calcining limestone could be large in absolute terms, making it a potentially significant part of industry emissions.

Notes that cement production is listed among the most polluting industries and mentions various pollution forms, implying multiple emission pathways (including chemical/process emissions).

A student can use this contextual point to justify investigating both combustion and chemical-process CO2 in cement manufacture to judge the relative significance of each.