Permanent hardness of water is caused by: MCQ with Answer and Explanation

Explanation:
Soap is made by saponification of triglycerides (fats/oils) which are esters of glycerol and long-chain fatty acids (e.g., stearic, palmitic, oleic). The sodium salt gives hard soap, potassium gives soft soap. The long hydrocarbon chain (hydrophobic) and carboxylate head (hydrophilic) provide cleaning action via micelle formation. Synthetic detergents are usually sodium salts of sulfonic acids or sulfate esters.

Explanation:
Biofuels are produced from biomass—recently living organisms or their metabolic byproducts. Examples: ethanol from sugarcane/corn, biodiesel from vegetable oils, biogas from organic waste. They are renewable and can reduce greenhouse gas emissions compared to fossil fuels. However, large-scale production may compete with food crops. Algae-based biofuels are also being researched.

Explanation:
Light catalyzes decomposition of H₂O₂. Dark bottles (amber) block light, stabilizing it. Often a stabilizer like urea or phosphoric acid is added. Metal containers may catalyze decomposition.