Important Viva Questions for Chemistry

Why don't we use HCl or HNO3 during titration of KMnO4?

• Because they react with KMnO4

• They are too strong

• They interfere with the reaction

• They are not available

What is the indicator used in the titration of KMnO4 vs oxalic acid?

• Phenolphthalein

• Methyl orange

• Bromothymol blue

• No indicator is used

In KMnO4 titrations, what is the endpoint?

• Color change to pink

• Formation of a precipitate

• No color change

• Color change to blue

In KMnO4 titrations, a brown ppt. is occasionally observed. Why is this so?

• It is a side reaction

• It indicates excess KMnO4

• It is due to impurities

• It is normal

Why do we heat oxalic acid solution containing sulphuric acid up to 50–60°C in the permanganate titration?

• To increase reaction rate

• To prevent precipitation

• To stabilize the solution

• It is not necessary

Why must the burette and pipette be rinsed with the solution with which they are filled?

• To avoid contamination

• To ensure accurate measurements

• To clean the equipment

• It is not necessary

Why is it customary to read the lower meniscus in colourless and transparent solutions and the upper meniscus in highly coloured solutions?

• To ensure accuracy

• It is a standard practice

• To avoid parallax error

• It does not matter

What is the role of sulphuric acid in the titration of KMnO4 with oxalic acid?

• It provides the acidic medium

• It acts as a catalyst

• It is a reducing agent

• It does not play a role

What color does KMnO4 exhibit in its concentrated form?

• Yellow

• Dark purple

• Pale pink

• Colorless

During the titration of KMnO4, what happens if the endpoint is overshot?

• The solution turns brown

• The solution remains colorless

• The solution turns blue

• The solution becomes cloudy