Eutrophication in water bodies is primarily caused by an excess of: MCQ with Answer and Explanation

Explanation:
Detergents do not form scum with Ca²⁺/Mg²⁺, so they clean effectively in hard water. Soaps form insoluble precipitates. Biodegradability varies; some detergents are non-biodegradable.

Explanation:
Stainless steel contains iron, chromium (min 10.5%), and often nickel. Chromium forms a passive oxide layer preventing rust. Nickel improves ductility and corrosion resistance. Molybdenum may be added for pitting resistance. Brass is Cu-Zn, bronze is Cu-Sn, solder is Pb-Sn.

Explanation:
C₂H₆ (ethane) follows the general formula CnH₂n+2 (n=2 gives C₂H₆), which is the formula for alkanes. Alkanes are saturated hydrocarbons with single bonds. Alkenes have CnH₂n (e.g., C₂H₄), alkynes CnH₂n-2 (e.g., C₂H₂), alcohols have –OH group. Ethane is a component of natural gas and is used to produce ethylene. Methane (CH₄) is the simplest alkane.