In the context of proposals to the use of hydrogen-enriched CNG (H-CNG) as fuel for buses in public transport, consider the following statements : 1. The main advantage of the use of H-CNG is the elimination of carbon monoxide emissions. 2. H-CNG as fuel reduces carbon dioxide 'and hydrocarbon emissions. 3. Hydrogen up to one-fifth by volume can be blended with CNG as fuel for buses. 4. H-CNG makes the fuel less expensive than CNG. Which of the statements given above is/are correct?

States that natural gas (CNG) is used as a transport fuel including for buses, establishing the real-world context where CNG-based blends would be applied.

A student could combine this with knowledge about vehicle fuel systems to ask whether CNG bus engines can accept modified gas compositions (e.g., blended gases).

Explains CNG composition (methane typically 80–90%), showing CNG is primarily a single light gas component that could in principle be mixed with other light gases.

Knowing methane dominance, a student could use gas property tables (e.g., energy content, flame speed) to estimate how adding 20% hydrogen would change fuel properties relevant to engines.

Describes methane (CH4) as the main component of CNG and reminds that hydrogen is a simple, single‑valence gas, highlighting chemical simplicity of both gases.

A student could combine this with standard facts about H2 (very low molecular weight, high flame speed) to infer possible effects of blending on combustion and engine tuning.

Gives an explicit example of fuel blending (15% methanol in gasoline) as an accepted policy/technical measure to reduce imports and emissions, showing blending fuels is a practical, regulated approach.

By analogy, a student could consider regulatory/technical precedent for blended fuels and investigate whether 20% volumetric blends are within typical policy/engineering ranges.

Defines different hydrogen types and links hydrogen production to natural gas (steam methane reforming), indicating hydrogen and natural gas are already connected in energy systems.

A student could use this to reason about supply-chain feasibility of co‑handling H2 and CNG and whether infrastructure or purity issues might limit blending percentages.

Identifies methane (CH4) as the primary component of CNG, so any blending replaces part of methane with hydrogen and thus changes the fuel composition.

A student could combine this with basic facts about energy content per unit mass/volume of methane vs hydrogen to estimate whether replacing methane with hydrogen would raise or lower fuel cost for the same vehicle range.

Defines different hydrogen production methods (grey, blue, green) and notes some are more carbon‑intensive—implying hydrogen production route strongly affects hydrogen cost.

A student could use common knowledge about the relative costs of hydrogen production routes (e.g., electrolysis vs steam methane reforming) to judge whether adding hydrogen would increase or decrease overall fuel cost compared with CNG.

Describes policy choices and concerns about relying solely on CNG for buses and the government's consideration of alternative fuels (dual‑fuel policy, low sulphur diesel).

A student could infer that fuel-cost comparisons are affected by supply, infrastructure and policy choices, and so should check local availability and subsidies for H‑CNG versus pure CNG to judge relative price for buses.

States that introduction of CNG in cities was a deliberate measure to reduce vehicular pollution and that governments may provide subsidies (for EVs mentioned) to encourage cleaner fuels.

A student could consider whether similar subsidies or incentives exist for hydrogen or H‑CNG that would alter on‑the‑pump prices compared with CNG.

Describes natural gas (CNG) uses and that expansion of gas infrastructure supports its use as transport fuel—implying infrastructure scale influences delivered cost.

A student could compare existing CNG infrastructure versus additional costs needed for hydrogen blending or H‑CNG dispensers to assess likely effect on fuel price for bus operators.