How to show that Formation Of Curd only takes place lukewarm milk
Answers
Answer:
n the setting of curd, milk changes into new substance, curd. This is an irreversible process that means milk cannot get back from curd. Formation of new substance and irreversible process shows that setting of curd is a chemical change.
Explanation:
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Things needed: Three cups, cold milk,lukewarm milk, hot milk and curd (3 teaspoons)
Method:
1. Take three cups and label them A, B and C.
2. Put cold milk in cup A, lukewarm milk in cup B and hot milk in cup C.
3. Add a spoonful of curd in each cup and stir them. Keep all the cups at a warm place for a few hours.
Observation: Curd is formed only in cup B containing lukewarm milk. No change is observed in cup A and cup C.
Conclusion: The curd which is added initially in all the cups contains some bacteria. When curd is mixed with lukewarm milk, these bacteria multiply and produce acidic products. Milk curdles and thickens to form curd. Bacteria are inactive in cold milk, so, no curd is formed. Hot milk kills bacteria, so, no curd is formed.