Virtual Labs

Chemical Sciences Virtual Chemistry Lab Experiments

Aim

Theory

Pretest

Procedure

Simulation

Posttest

References

Feedback

Aim

Theory

Pretest

Procedure

Simulation

Posttest

References

Feedback

Caffeine content in tea and coffee

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Beginner

Intermediate

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1. Rf value is less than one because -

a: Distance covered by the solute is more than solvent front Explanation

Explanation

b: Distance covered by solvent front is more than distance covered by solute Explanation

Explanation

c: Both of them Explanation

Explanation

d: None of them Explanation

Explanation

2. Rf value is close to 1, then what happens?

a: Good separation occurs Explanation

Explanation

b: No separation occurs Explanation

Explanation

c: Separation does not depend on Rf Explanation

Explanation

d: None of them Explanation

Explanation

3. Rf value is affected by -

a: Polarity of solvent Explanation

Explanation

b: Saturation period of chamber Explanation

Explanation

c: pH of the solution Explanation

Explanation

d: All of the above Explanation

Explanation

4. If TLC spots are too high, i.e., too near the solvent front, then what can I do now?

a: Increase the polarity of solvent Explanation

Explanation

b: Decrease the polarity of solvent Explanation

Explanation

c: Increase the plate size Explanation

Explanation

d: All above Explanation

Explanation

5. Do impurities affect the Rf values?

a: Yes, always Explanation

Explanation

b: Yes, sometimes Explanation

Explanation

c: No Explanation

Explanation

d: None Explanation

Explanation

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