HOUSEHOLD CHEMISTRY — Composition of cleaning agents. Question: Modern detergents used for cleaning clothes and utensils commonly contain which class of active surfactants?

Introduction / Context:Detergents clean by lowering surface tension and forming micelles that trap oily dirt. The key component is the surfactant molecule, with a hydrophobic tail and a hydrophilic headgroup. Recognizing the chemical family used in most household detergents helps explain their effectiveness and compatibility with hard water.

Given Data / Assumptions:

• We focus on the principal active surfactant in typical laundry and dishwashing detergents.
• Common examples include linear alkylbenzene sulphonates (LAS).
• Other listed ions (bicarbonate, nitrate, silicate) may appear as builders or additives but are not the core surfactant class.

Concept / Approach:Anionic sulphonate surfactants (–SO₃⁻ group) such as sodium dodecylbenzene sulphonate dominate due to good detergency and foaming. They perform well in a range of water conditions and are relatively economical. Bicarbonates and silicates may assist as builders or pH buffers, but they do not provide the primary micelle-forming action. Heavy-metal anions like bismuthates are unrelated to household detergency.

Step-by-Step Solution:Identify the functional role needed: surface-active cleaning → surfactant.Match the family widely used in consumer detergents → sulphonate-based anionic surfactants.Eliminate ions used for other roles (buffers/builders) or not used at all in such products.

Verification / Alternative check:Product ingredient lists and safety data sheets typically list “linear alkylbenzene sulfonate” or “sodium laureth sulfate,” both sulphonate/sulfate anionic surfactants.

Why Other Options Are Wrong:A) Bicarbonates can act as mild alkalis/builders but are not the primary detergents.B) Bismuthates are not used in consumer detergents.D) Nitrates are oxidizing salts/fertilizer components, not detergent actives.E) Silicates can be builders/anti-corrosion agents; not the main surfactants.

Common Pitfalls:Confusing builders and fillers with the actual surfactant. The cleaning action fundamentally depends on the sulphonate/sulfate headgroup amphiphiles.

Final Answer:sulphonates (anionic surfactants)