12th Chemistry Chapter 1 – 3 Mark Questions (Important & Repeated – TN Board)
Prepare for exams with 12th Chemistry Chapter 1 (Metallurgy) important 3 mark questions. This collection includes most repeated and previously asked questions based on TN Board exams, helping students revise key concepts quickly and score better.
Metallurgy – 3 Mark Questions
Most Repeated 3 Marks
Note : Number next to questions tells, how many times it has been repeated in past few years
1.Explain zone refining process with an example?(4)
- This method is based on the principles of fractional crystallisation.
- When an impure metal is melted and allowed to solidify, the impurities will prefer to be in the molten region.
- In this process the impure metal is taken in the form of a rod.
- One end of the rod is heated using a mobile induction heater which results in melting of the metal on that portion of the rod.
- When the heater is slowly moved to the other end the pure metal crystallises while the impurities will move on to the adjacent molten zone formed due to the movement of the heater.
- As the heater moves further away, the molten zone containing impurities also moves along with it.
- The process is repeated several times by moving the heater in the same direction again and again to achieve the desired purity level.
- This process is carried out in an inert gas atmosphere to prevent the oxidation of metals .
- Elements such as germanium (Ge), silicon (Si) and galium (Ga) that are used as semiconductor are refined using this process.
2.List out the observations from Ellingham diagram?(2)
- For most of the metal oxide formation, the slope is positive.
- Oxygen gas is consumed during the formation of metal oxides which results in the decrease in randomness. Hence, ΔS becomes negative and it makes the term, TΔS positive in the straight line equation.
ΔG = ΔH – TΔS
- The graph for the formation of carbon monoxide is a straight line with negative slope. In this case ΔS is positive as 2 moles of CO gas is formed by the consumption of one mole of oxygen gas. It indicates that CO is more stable at higher temperature.
- As the temperature increases, generally ΔG value for the formation of the metal oxide become less negative and becomes zero at a particular temperature. Below this temperature, ΔG is negative and the oxide is stable and above this temperature ΔG is positive. This general trend suggests that metal oxides become less stable at higher temperature and their decomposition becomes easier.
- There is a sudden change in the slope at a particular temperature for some metal oxides like MgO, HgO. This is due to the phase transition (melting or evaporation).
3.Give the limitations of Ellingham diagram?(2)
1. Ellingham diagram is constructed based only on thermodynamic considerations. It gives information about the thermodynamic feasibility of a reaction. It does not tell anything about the rate of the reaction. More over, it does not give any idea about the possibility of other reactions that might be taking place.
2. The interpretation of ΔG is based on the assumption that the reactants are in equilibrium with the products which is not always true.
12th Chemistry Chapter 1 Metallurgy Important 3 Marks Questions
Welcome to our collection of 12th Chemistry Chapter 1 Metallurgy Important 3 Marks Questions prepared from previous year public question papers and important board exam questions. These questions are highly useful for Tamil Nadu State Board Class 12 students preparing for public examinations, quarterly exams, half-yearly exams, and revision tests.
Metallurgy is one of the most important chapters in Class 12 Chemistry. This chapter explains the extraction of metals from ores, concentration methods, roasting, calcination, refining techniques, Ellingham diagram, and electro metallurgy. Many direct and repeated 3 mark questions are asked from this chapter in board examinations.
Why Practice 3 Mark Questions?
- Improves conceptual understanding
- Helps in public exam preparation
- Covers repeated board questions
- Boosts confidence during revision
- Enhances answer presentation skills
Important Topics Covered
- Concentration of Ores
- Roasting and Calcination
- Ellingham Diagram
- Refining of Metals
- Froth Flotation Process
- Electro Metallurgy
Previous Year Public Exam Questions
The important 3 marks questions given here are collected from previous year Tamil Nadu 12th Chemistry public question papers. Practicing these questions regularly can help students understand the exam pattern and frequently asked concepts from the Metallurgy chapter.
Students are advised to write answers in a step-by-step manner with proper chemical equations and key points to score full marks in the examination.
More 12th Chemistry Study Materials
Explore more useful study materials for Class 12 Chemistry:
- Additional 1 Mark Questions
- 2 Marks and 5 Marks Questions
- Book Back Answers
- Chapter Wise Notes
- Public Exam Important Questions
- Previous Year Question Papers
- Most Expected Questions and Answers
Practice daily and revise previous year questions regularly to score high marks in the 12th Chemistry public examination.
