Hard water does not produce good lather with soap because it contains: MCQ with Answer and Explanation

Explanation:
Bakelite is a thermosetting phenol-formaldehyde resin with excellent heat resistance and electrical insulation properties, making it suitable for switches, handles, and electrical fittings. Polythene and PVC are thermoplastics that soften on heating. Polystyrene is brittle and not highly heat resistant. Thermosets do not melt upon reheating.

Explanation:
Sodium carbonate (Na₂CO₃), also called soda ash, is a key ingredient in glass manufacturing. It lowers the melting point of silica (SiO₂) and provides sodium oxide. The glass batch consists of sand (SiO₂), soda ash (Na₂CO₃), and limestone (CaCO₃). Sodium chloride is table salt, potassium nitrate used in gunpowder, ammonium chloride in batteries/leclanche cells.

Explanation:
In displacement reactions, a more reactive element displaces a less reactive one from its compound. Here, iron (more reactive than copper) displaces copper from copper sulfate. A is combination; B is decomposition; D is neutralization (double displacement).