The calorific value of a fuel is measured using a: MCQ with Answer and Explanation

Explanation:
Froth flotation separates sulfide ore particles from gangue by using oil and water. The ore particles adhere to the froth and float, while gangue sinks. Used for ZnS, PbS, CuFeS₂. Magnetic separation for magnetite, leaching for bauxite.

Explanation:
Boyle's law: P₁V₁ = P₂V₂. So P₂ = P₁(V₁/V₂) = P₁(10/20) = P₁/2. Pressure is halved. If volume doubles, pressure halves, assuming constant temperature and amount. This is an inverse relationship.

Explanation:
Bakelite is a thermosetting plastic (phenol-formaldehyde resin). Once set, it cannot be remolded by heating because its polymer chains are cross-linked. Polyethylene, PVC, and nylon are thermoplastics—they can be repeatedly softened by heat and hardened on cooling. Thermosetting plastics are used for electrical switches, handles, and adhesives. Vulcanized rubber is also thermoset.