Q.What do you understand by the terms:

1. Hydrogen economy: a proposed future energy system in which dihydrogen (produced cleanly and stored/transported efficiently) is used as the principal energy carrier/fuel in place of fossil fuels, powering vehicles, generating electricity, and so on. Since burning H2 produces only water, this is envisioned as a clean, non-polluting, efficient alternative energy system.
2. Hydrogenation: the chemical addition of dihydrogen across a multiple (double or triple) bond of an unsaturated organic compound, usually in the presence of a catalyst (Ni, Pd or Pt), converting it into a saturated compound. A familiar example is the hydrogenation of unsaturated vegetable oils to give solid, saturated fats (vanaspati/hydrogenated ghee).
3. Syngas ("synthesis gas" / water gas): a mixture of carbon monoxide and dihydrogen, prepared industrially by passing steam over red-hot coke:

   $C(s) + H_2O(g) \xrightarrow[1270\,K]{} CO(g) + H_2(g)$

   It is called "synthesis gas" because it is used as the starting material for synthesising methanol and a range of other hydrocarbons, and is also an important commercial source of dihydrogen.
4. Water-gas shift reaction: the catalysed reaction of the CO present in syngas with additional steam, converting it into more dihydrogen (plus CO2):

   $CO(g) + H_2O(g) \xrightarrow[673\,K]{catalyst} CO_2(g) + H_2(g)$

   This is used industrially to increase the overall yield of H2 obtainable from the initial coal-steam gasification, with the CO2 by-product subsequently removed by scrubbing (e.g., with sodium arsenite solution). …

Define each term concisely with its defining reaction/process and one real application: hydrogen economy (energy-system concept), hydrogenation (catalytic addition reaction), syngas (CO+H2 mixture and its origin), water-gas shift (th …

• Confusing "syngas" (the raw CO+H2 mixture from gasification) with the "water-gas shift reaction" (the subsequent step that further converts CO into more H2) — they are related but distinct. …