Question

Complete the table 2.2 on page no 26 of cbse science text book.

Answer 1

Answer:

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Explanation:

⇒ Objective

To determine the pH values of the given solutions with the help of pH paper.

⇒ Materials Required

Saliva, lemon juice, tomato juice, carrot juice, soda water, coffee, tea water, 1 M NaoH solution, 1 M HCl solution and pH paper.

⇒ Procedure

Take different solutions in different test tubes,

Now, place one or two drops of lemon juice on a pH paper strip.

Note the colour obtained.

Repeat the same procedure with each given solution using a new pH paper strip and note the colours obtained.

⇒ Observation

Saliva (before meal) :- Green ; pH = 7.4 ; (Weakly alkaline) Basic.

Saliva (after meal) :- Depends upon the food eaten.

Lemon juice :- Pink ; pH = 2.5 ; Acidic.

Colourless aerated drink :- Yellow/Green ; pH = 5.0 - 6.0 ; Acidic

Carrot juice :- Yellow/Green ; pH = 5.0 - 6.0 ; Acidic.

Coffee :- Yellow ; pH = 5.0 ; Acidic.

Tomato juice :- Orange ; pH = 4.1 ; Acidic.

Tap water :- Green ; pH = 6.5 - 8.5 (7.0) ; Neutral

1 M NaOH :- Purple ; pH = 14.0 ; Strongly Alkaline (Basic)

1 M HCl :- pH = 0.0 ; Acidic.

⇒ Conclusion

Solutions having pH value less than 7 are acidic while those having pH value greater than 7 are basic in nature. As pH value of water is 7, therefore it is considered neither acidic nor basic but neutral.

Hope it helps!