The main constituent of CNG is: MCQ with Answer and Explanation

Explanation:
Magnesium reacts with hot water or steam to form MgO/Mg(OH)₂ and H₂, but very slowly with cold water (thin layer of insoluble hydroxide inhibits reaction). Sodium, potassium, and calcium react vigorously with cold water. Aluminium, zinc, iron react with steam but not cold water. Reactivity with water follows the series: K, Na, Ca (cold water); Mg, Al, Zn, Fe (steam).

Explanation:
Distillation separates liquids based on their different boiling points. The mixture is heated; the component with lower boiling point vaporizes first, is condensed and collected. Fractional distillation is used for smaller boiling point differences. Filtration separates solids from liquids. Sublimation separates sublimable solids. Magnetic separates magnetic substances.

Explanation:
Magnesium oxide (MgO) is an ionic compound. Magnesium (2,8,2) loses two electrons to become Mg²⁺, and oxygen (2,6) gains two electrons to become O²⁻. This electron transfer forms an electrovalent (ionic) bond. Covalent bonds involve sharing (e.g., H₂O).