Chemistry Viva Questions Class 12 with Answers
The CBSE Class 12 Chemistry practical exam includes both actual experiments and a Viva Voce session. The practical part evaluates your ability to perform experiments, while the Viva Voce focuses on your knowledge of chemistry principles and concepts. The Viva Voce can be daunting because it’s hard to predict the questions. But with solid preparation, you can handle it well and even score high marks.
In this article, we offer a detailed preparation guide and a compilation of essential chemistry viva questions class 12 for 2024. Practicing these chemistry practical questions and answers can significantly improve your readiness for both the practical experiments and the Viva Voce part of your chemistry exam. Make sure to go through these chemistry viva questions class 12 and familiarize yourself with typical chemistry practical questions and answers to boost your confidence and performance.
What is a standard solution?
Answer: A standard solution is one where the concentration is accurately known.
What is a normal solution?
Answer: A normal solution contains exactly one gram-equivalent of the solute per liter.
What is the equivalent mass of KMnO4 in acidic conditions?
Answer: When KMnO4 acts as an oxidizing agent in acid, it loses 5 electrons per molecule, so its equivalent mass is one-fifth of its molecular weight.
Is sodium hydroxide a primary standard?
Answer: No.
Are molality and molarity the same?
Answer: No, molality measures the moles of solute per 1000 grams of solvent, whereas molarity measures moles per liter of solution.
What is the normality of a 0.10M solution of KMnO4?
Answer: It’s 0.5N because you multiply the molarity by 5.
How much 10M HCl is needed to make 1L of 1M HCl by dilution?
Answer: You need 0.1L of 10M HCl.
What is the basicity of H2SO4?
Answer: The basicity of H2SO4 is 2.
How are normality, molarity, molecular mass, and equivalent mass related?
Answer: Normality multiplied by equivalent mass equals molarity multiplied by molecular mass.
Why should the balance door be closed during weighing?
Answer: To avoid vibrations from the operator’s breath, which can cause inaccuracies.
What is the maximum weight a chemical balance can measure?
Answer: Up to 100 grams.
What is the weight of a rider in a balance?
Answer: 10 mg.
What is a rider used for in a balance?
Answer: It’s used to measure weights smaller than 10 mg.
What is the principle of volumetric analysis?
Answer: It involves measuring the concentration of a solution by its reaction with a measured amount of another solution.
What is titration?
Answer: It’s the process of adding one solution to another until a chemical reaction is completed.
What is an indicator?
Answer: An indicator is a substance that changes color to signal the end of a reaction.
What is the endpoint in titration?
Answer: It’s the point at which the reaction between the solutions is just completed.
Why should you not rinse a titration flask?
Answer: Rinsing can leave residual liquid that might alter the measured volume.
What distinguishes primary from secondary standard substances?
Answer: Primary standards are highly pure, stable, don’t absorb or lose water, and keep well over time, unlike secondary standards.
Why should burettes and pipettes be rinsed with the solutions they’ll contain?
Answer: To remove any residual water that might dilute the solution being measured.
Why do you read the lower meniscus with clear solutions and the upper meniscus with colored solutions?
Answer: The lower meniscus is easier to read with clear solutions, while the upper is used for colored solutions where the lower isn’t clear.
What is a molar solution?
Answer: A molar solution contains one mole of a substance per liter of solution.
Why shouldn’t the last drop from a pipette be blown out?
Answer: Because that drop is not part of the measured volume.
Why should you not hold a pipette by the bulb?
Answer: Holding the bulb can heat the pipette slightly, causing expansion and measurement errors.
What are acidimetry and alkalimetry?
Answer: They are methods of measuring the concentration of acids and bases through titration.
What is permanganometry?
Answer: It’s a type of titration that uses KMnO4 as an oxidizing agent.
In a reaction with KMnO4 and FeSO4, which is the oxidizing and reducing agent?
Answer: KMnO4 is the oxidizing agent and FeSO4 is the reducing agent.
What indicator is used in KMnO4 titrations?
Answer: None, because KMnO4 serves as its own indicator.
Why does KMnO4 act as its own indicator?
Answer: KMnO4 shows a pink color when excess is present after the reaction is complete.
What is the endpoint color change in KMnO4 titrations?
Answer: The solution changes from colorless to a permanent light pink.
Why is Mohr’s salt preferred over ferrous sulphate as a primary standard?
Answer: Mohr’s salt is stable and doesn’t oxidize as quickly as ferrous sulphate.
Why add a few drops of H2SO4 when preparing a Mohr’s salt solution?
Answer: To prevent the hydrolysis of ferrous sulphate.
Why shouldn’t you use a rubber pinch cock in KMnO4 titrations?
Answer: KMnO4 can react with and degrade the rubber.
