With reference to two non-conventional energy sources called 'coalbed methane' and 'shale gas', consider the following statements : 1. Coalbed methane is the pure methane gas extracted from coal seams, while shale gas is a mixture of propane and butane only that can be extracted from fine-grained sedimentary rocks. 2. In India, abundant coalbed methane sources exist, but so far no shale gas sources have been found. Which of the statements given above is/are correct?

States that natural gas is a mixture of gaseous hydrocarbons and that methane alone may make up 80–90%, with other gases like ethane, propane and butane present.

A student could generalize that subsurface hydrocarbon gases (including those from coal seams) are often mixtures rather than pure methane, so coalbed methane plausibly contains other hydrocarbons and should be tested for composition.

Notes methane is emitted from natural gas systems (implying natural gas systems contain methane within a broader gas context).

Using the idea that methane occurs within larger natural gas systems, a student could infer coalbed gas reservoirs may similarly host methane alongside other gases and leaks would reflect mixture behavior.

Explains methane as a major component of bio-gas and CNG, implying these fuels are characterized by a primary component (methane) plus other constituents.

A student could analogize that ‘coalbed methane’ like biogas/CNG is likely described by its dominant component (methane) but not necessarily pure, so composition analysis is needed.

Describes gas production from coal (coal gasification) as a source of hydrogen and other products, implying coal-related processes produce mixed gases.

A student could extend that coal seams and coal-derived gases tend to yield mixtures in processing, suggesting coalbed methane reservoirs may contain multiple gaseous species rather than only CH4.

States that 'natural gas' major constituent is methane (80–90%) and that other gases include ethane, propane and butane, showing typical natural gas is a multi-component hydrocarbon mixture.

A student could extend this by noting shale gas is a form of natural gas and therefore likely contains methane and other hydrocarbons, not only propane and butane.

Defines petroleum as a mixture of hydrocarbons in solid, gaseous or liquid form, illustrating that subsurface hydrocarbon accumulations are commonly multi-component mixtures.

Use this rule to infer shale gas (a subsurface hydrocarbon gas) is similarly a mixture of several hydrocarbons rather than only two components.

Gives the general definition of a mixture: two or more substances mixed together whose components retain properties, indicating gases labelled 'mixtures' normally contain multiple pure substances.

Apply this definition to 'shale gas' to expect multiple gaseous hydrocarbon components rather than a binary-only composition.

Lists the series of alkanes (methane, ethane, propane, butane, pentane, hexane), showing common gaseous hydrocarbons include methane and ethane as well as propane/butane.

A student could recall that natural/shale gas typically contains members from this homologous series (especially methane/ethane), so composition limited to only propane and butane would be atypical.

Explains the homologous series pattern (successive alkanes differ by CH2), implying natural gas mixtures can include a range of related hydrocarbons of varying chain lengths.

Use the pattern to reason shale gas can plausibly include several consecutive alkanes (methane, ethane, propane, etc.) rather than exclusively two specific ones.

Establishes that India is a major coal producer (third largest) and gives large coal production/reserve figures, implying substantial coal seam volume.

A student could combine this with the basic fact that coalbed methane (CBM) is produced from coal seams to infer that large coal reserves increase the potential for CBM resources and then seek CBM-specific surveys for confirmation.

States that over 98% of India's coal reserves belong to the Gondwana period and that this coal is mainly bituminous/anthracite (higher carbon content).

Knowing CBM is commonly associated with coal seams (often Gondwana coals in India), a student could use this to hypothesize which coal types/regions are more likely to host CBM and then check geological CBM assessments.

Says coal is India's most abundantly available fossil fuel and is central to energy supply, highlighting the scale and importance of coal resources.

A student could treat abundant coal as a necessary precondition for significant CBM potential and then look up targeted CBM exploration data to test whether that potential is realized.

Notes that coal distribution in India is highly uneven and lists the main states with good quality coal (Jharkhand, Chhattisgarh, Madhya Pradesh, Odisha, West Bengal).

A student could combine this with a map to identify where CBM might be geographically concentrated and then compare with records of CBM exploration/fields in those states.

Indicates that tertiary (lignite/brown) coal constitutes only a small portion (total tertiary reserves 1,588 million tonnes) and lists states where this occurs.

Since CBM potential depends on coal seam type and maturity, a student could use this to focus CBM expectations on Gondwana (not tertiary) coal areas and then consult geological/maturity data to refine likelihood.

Lists the ten sedimentary basins in India where petroleum and natural gas have been discovered — these identify the kinds of basins where unconventional resources like shale gas might be sought.

A student could map these basins against global shale-hosting sedimentary basins (using a world/regional geologic map) to assess which Indian basins are plausible targets for shale gas exploration.

Notes discoveries of petroleum and natural gas in delta/offshore regions and states, and explicitly states 'strong possibilities' of deposits offshore in several regions — indicating active exploration and potential for non-conventional finds.

One could check exploration activity and well logs in the named basins (e.g., Godavari-Krishna) to see if shale sequences were targeted or identified by 2014.

Mentions new reserves of natural gas discovered in the Krishna-Godavari basin and expansion of gas infrastructure — implying recent exploration successes in basins that could also host unconventional gas.

Compare the timing/location of these recent discoveries with industry reports on shale assessments to judge whether shale gas was identified by 2014 in those areas.

Describes Gondwana (Mesozoic) formations and associated coal and organic-rich sediments; such sedimentary sequences can be source rocks for hydrocarbons and, in other countries, host unconventional gas.

A student could use basic stratigraphic knowledge to ask whether organic-rich Gondwana shales occur in listed basins and whether these were evaluated for shale gas by 2014.

Gives national production figures for natural gas for 2014–15, showing active gas production but no mention of shale — implying conventional gas dominated production at that time.

One could infer that if shale gas had been a significant find by 2014 it might have been noted alongside production data, so checking contemporaneous production reports or surveys could help confirm presence/absence.