Exercise, 8th Sci., 12. Introduction to Acid & Base.

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या धड्यातील जास्तीत जास्त भाग आयुष्यभर लक्षात ठेवावा असा आहे. त्यामुळे या पाठाचे वाचन, लेखन, मनन आणि चिंतन व्यवस्थित करावे.

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1. An acid is such a substance that gives ... ions in a solution state.

2. Write properties of alkalies.

3. Compounds imparting sour taste are called ... .

4. DNA (deoxyribonucleic acid) is an acid present in our body that decides ... property.

5. Substance: Acids

     / Source       (Natural/organic)

        

•  Vinegar 
•  Orange 
•  Tamarind 
•  Tomatoes 
•  Curd
•  Lemon 

6. ... indicators can also be prepared from red cabbage, radish, tomato, and similarly from hibiscus and rose.

7. The taste of distilled water is .... .

8. Write 4 uses of acids.

9. Explain neutralization with one chemical reaction.

10. Blue litmus paper ... red on dipping in acid.

11. ... acid is used for the preparation of different types of chloride salts.

12. Acids present in foodstuffs are called natural acids or ... acids.

13. Hydrochloric acid is present in our ... . It helps to ease the digestion process.

14. Phenolphthalein remains colorless in acid and becomes ... in alkali.

15. Write 3 examples of ‘mineral acids.'

16. The substances that are neither acidic nor basic and are chemically ... in nature.

17. Dil. ... is used for sterilization of water.

18. HCl + NaOH ----> ... + H₂O

19. Methyl orange indicator becomes pink in acid and ... in alkali.

20. The distilled ... is neither acidic nor basic.

21. Write examples of some acids.

22. Never add ... to the concentrated sulphuric acid.

23. Litmus paper is made by an extract of the ... plant.

24. Red litmus turns blue by ... .

25. Write properties of acid.

26. From the name of the base, write the formula of the following substances. 

• Sodium hydroxide/Caustic soda 
• Potassium hydroxide / Potash 
• Calcium hydroxide/lime water 
• Magnesium hydroxide / milk of magnesia
• Ammonium hydroxide

27. Classify following substances into

acidic, basic and neutral groups—HCl, NaCl, MgO, KCl, CaO, H₂SO₄,  HNO₃,  H₂O,  Na₂CO₃

28. Proteins, which are part of our body cells, are made up of ... acids.

28.1 Antacids are used to control hyperacidity. Antacid medicine contains milk of magnesia, and its formula is ... .

29. Write chemical names from given formulae.

H₂SO₄, Ca(OH)₂, HCl, NaOH, KOH, NH₄OH

30. The substances that change their colors in the presence of acid or base are called ‘...’.

31. From the name of the base, write the use of the following substances. 

•  Sodium hydroxide/Caustic soda 
•  Potassium hydroxide / Potash 
•  Calcium hydroxide/lime water 
•  Magnesium hydroxide / milk of magnesia
•  Ammonium hydroxide

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“भर दुपारी” आणि “भर रात्री” ला इंग्रजीत कसे म्हणतात?

✅ भर दुपारी

इंग्रजी: At noon / In the afternoon (exact noon = at noon)

अर्थ: अगदी दुपारी — 12:00 PM चा वेळ

✅ भर रात्री

इंग्रजी: At midnight

अर्थ: अगदी रात्री 12:00 — 12:00 AM चा वेळ

सोप्या उदा. सह:

मी भर दुपारी जेवण करतो.

→ I have lunch at noon.

तो भर रात्री घरी पोहोचला.

→ He reached home at midnight.

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