The process of separating petroleum into various fractions is called: MCQ with Answer and Explanation

Explanation:
The chief impurity in iron ores (hematite, magnetite) is silica (SiO₂), which is acidic gangue. In the blast furnace, limestone (CaCO₃) is added as flux; it decomposes to CaO, which combines with silica to form fusible calcium silicate slag: CaO + SiO₂ → CaSiO₃. This slag floats on molten iron and is removed. Alumina may also be present but silica is the primary impurity.

Explanation:
A positive catalyst increases reaction rate by lowering activation energy. Decreasing temperature generally slows reactions. Decreasing concentration reduces collision frequency, lowering rate. Larger pieces have less surface area, slower reaction. Other rate-increasing factors: increasing temperature, increasing pressure (for gases), using finely powdered solids, and light for photochemical reactions.

Explanation:
Aluminium oxide (Al₂O₃) reacts with both acids and bases, so it is amphoteric. Na₂O and MgO are basic; CuO is basic. ZnO is also amphoteric.