I. General Cleanliness

1. Always use clean apparatus
2. Keep bench clean and dry
3. Use tap water to wash apparatus
4. Use a clean dropper to transfer reagent to test tube
5. Do not contaminate the mouth of test tube with reagent (very likely to come into contact with litmus and gives wrong colour changes when testing for gas)
6. Use clean, dry fingers to handle litmus paper
7. User deionised water to prepare all test solutions required
8. During the course of work, place dirty test tubes in a definite palace, preferably in a beaker and wash them at convenient intervals.

- Contamination often gives wrong observations and conclusions -

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