The valency of phosphorus in PCl₅ is: MCQ with Answer and Explanation

Explanation:
Ethylene glycol (1,2-ethanediol) is the main component of antifreeze, lowering the freezing point of water. Methanol is toxic, ethanol can be used but evaporates, glycerol is viscous. Ethylene glycol is poisonous if ingested. Propylene glycol is a safer alternative.

Explanation:
Na+, Mg2+, Al3+, and F- are isoelectronic species, each having 10 electrons. For isoelectronic ions, the ionic radius decreases as the nuclear charge (number of protons) increases because the greater positive charge pulls the same number of electrons closer. F- has the lowest nuclear charge (9), so it has the largest radius.

Explanation:
High-concentration H₂O₂ (e.g., 80-90%) decomposes rapidly in the presence of a catalyst to produce superheated steam and oxygen: 2H₂O₂ → 2H₂O + O₂ + heat. This generates high-pressure gas used for propulsion (monopropellant) or as oxidizer in bipropellant systems. It is not a fuel; it provides oxygen for combustion. It must be handled carefully due to instability.