In descriptive organic chemistry, ethane (C2H6) is often said to have a slightly ______ character in its taste and odour when detected in high concentration. Which word best completes this statement?

Introduction / Context:
This general knowledge chemistry question is about a descriptive property of ethane gas, a simple alkane with formula C2H6. Although pure ethane is usually described as colourless and almost odourless, when such small hydrocarbons are detected at higher concentrations, they can be perceived as having a faintly sweet or gasoline like character. Examinations often use this traditional description to distinguish ethane from substances associated with sour or salty tastes.

Given Data / Assumptions:

• The compound in question is ethane gas, a small saturated hydrocarbon.
• The question describes ethane as having a slightly characteristic taste or odour.
• Possible descriptive words include sweet, bitter, sour, salty and pungent.
• We are using conventional qualitative descriptions used in basic chemistry texts, not encouraging tasting of chemicals in practice.

Concept / Approach:
In everyday chemistry language, many low molecular mass hydrocarbons and related organic solvents are described as having a mild, sweetish smell or taste when compared with strongly bitter or sour compounds. Ethane is used as a fuel gas and is often present in natural gas mixtures. While it is not advisable to taste laboratory gases, the traditional description is that ethane has a faintly sweet character rather than a bitter, sour or salty one. This convention is reflected in many objective type questions in chemistry examinations.

Step-by-Step Solution:
1) Recognise that ethane is a simple alkane consisting only of carbon and hydrogen atoms.2) Many alkanes are colourless gases at room temperature and are described as having mild or faintly sweet odours, especially when compared to sharp or irritating gases like ammonia or chlorine.3) Bitter or sour characteristics are usually associated with certain ionic compounds, acids or specific organic substances, not with neutral hydrocarbons like ethane.4) Salty taste is characteristic of many ionic solids in solution, particularly sodium chloride, and does not apply to a non polar gas like ethane.5) Pungent odours are more consistent with gases such as ammonia, sulphur dioxide or chlorine, which are very different chemically from ethane.6) Therefore, the most suitable word among the given options to describe the slight character of ethane is sweet.

Verification / Alternative check:
Descriptive tables of common gases often summarise ethane as colourless and nearly odourless, sometimes noting a faintly sweet smell at higher concentrations, similar to other light alkanes. While modern safety practice forbids tasting chemicals, historic descriptions still use the term sweet for hydrocarbons such as ethane, propane and butane, in contrast to the clearly sour taste of acids or the salty taste of ionic solutions. These references support choosing sweet rather than any of the other adjectives listed in the options.

Why Other Options Are Wrong:
Bitter: Bitter tastes are more typical of certain alkaloids or specific organic molecules, not simple neutral hydrocarbons like ethane.
Sour: Sour taste is characteristic of acids that produce hydrogen ions in solution, and ethane is a non acidic hydrocarbon.
Salty: Salty taste comes from ionic compounds in water, especially sodium and potassium salts, which is not relevant for gaseous ethane.
Pungent: Strongly irritating gases such as ammonia or sulphur dioxide are labelled pungent, whereas ethane is relatively mild in odour.

Common Pitfalls:
Because modern laboratory practice discourages tasting or smelling chemicals directly, many learners are unfamiliar with these traditional qualitative descriptions and may guess randomly. A practical approach for exam questions is to associate sour with acids, salty with ionic salt solutions, pungent with strongly irritating gases and sweet with many volatile organic liquids and gases. Using this pattern, ethane is most reasonably described as slightly sweet in character among the given options.

Final Answer:
Ethane gas is described as having a slightly sweet character in its taste and odour in traditional chemistry descriptions.