The separation technique that uses a porous barrier to separate solids from liquids is: MCQ with Answer and Explanation

Explanation:
The critical temperature (Tc) is the temperature above which a gas cannot be liquefied, regardless of how much pressure is applied. Above Tc, the kinetic energy of the molecules is too high for intermolecular forces to hold them together in a liquid state, even under extreme pressure.

Explanation:
CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂↑. Carbon dioxide turns limewater milky. This is a test for carbonates and bicarbonates. The reaction is used in laboratory preparation of CO₂.

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.