Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Matter is classified into pure substances (elements and compounds) and mixtures.
An Element is a pure substance consisting of only one type of atom, such as Iron () or Oxygen ().
A Compound is formed when two or more elements chemically combine in a fixed ratio by mass, such as Water () or Carbon Dioxide ().
A Mixture contains two or more substances physically mixed together without any chemical bond, like air or salt solution.
Minerals are naturally occurring inorganic substances found in the Earth's crust with a definite chemical composition and physical properties.
Ores are specific minerals from which one or more metals can be extracted profitably and conveniently. It is said that 'All ores are minerals, but all minerals are not necessarily ores'.
The process of extracting pure metals from their ores is known as Metallurgy.
Common types of ores include Oxide ores (e.g., ), Sulphide ores (e.g., ), and Carbonate ores (e.g., ).
📐Formulae
💡Examples
Problem 1:
Identify the metal present in the ore known as Galena () and categorize it based on its chemical composition.
Solution:
The metal present in Galena () is Lead (). It is categorized as a Sulphide ore.
Explanation:
The formula indicates the presence of Lead () bonded with Sulphur (). Since the anion is sulphur, it is a sulphide mineral.
Problem 2:
Why is Bauxite () considered an ore of Aluminium, while common clay (which also contains Aluminium) is only considered a mineral?
Solution:
Bauxite is an ore because Aluminium can be extracted from it profitably and easily, whereas extraction from clay is difficult and expensive.
Explanation:
By definition, an ore must allow for the economical extraction of a metal. While many minerals contain metal atoms, only those with high concentrations and feasible extraction methods qualify as ores.
Problem 3:
Represent the formation of Magnesium Oxide from its elements using a chemical equation.
Solution:
Explanation:
Magnesium () reacts with Oxygen () to form the compound Magnesium Oxide (). This shows how two elements combine chemically to form a compound.