Urea contains what percentage of nitrogen approximately? MCQ with Answer and Explanation

Explanation:
Ozone (O₃) has one coordinate bond; a central oxygen donates a lone pair to another oxygen. CH₄, NH₃, H₂O have ordinary covalent bonds, though NH₃ can donate a pair to form NH₄⁺.

Explanation:
The long hydrocarbon chain (tail) of soap is non-polar and hydrophobic, so it dissolves into the oily/greasy dirt particle. The ionic head (hydrophilic) remains in the water. This forms a micelle around the dirt, emulsifying it and allowing it to be washed away. The tail-dirt interaction is via van der Waals forces.

Explanation:
Highly reactive metals (K, Na, Ca, Mg, Al) are extracted by electrolysis of their fused (molten) salts because chemical reducing agents cannot reduce their ores. For sodium, Down's process: electrolysis of molten NaCl with CaCl₂ to lower melting point. Iron is extracted by smelting (blast furnace). Copper and zinc can be extracted by reduction with coke or electrolytic refining of impure metal.