Page 49 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

3. Litmus is extracted from ..................... .

(a) Algae (b) Fungi (c) Lichens (d) None of these

Ans. (c)

4. Glass cleaning liquids are used to clean mirrors and glasses. They will change the

colour of litmus from ..................... .
(a) Blue to red (b) Red to blue

(c) Blue to orange (d) Orange to blue

Ans. (b)

5. Turmeric is a natural indicator. Its colour in acidic and basic solutions is .................... .

(a) Yellow in both (b) Yellow in acid and red in base
(c) Pink in acid and yellow in base (d) Red in acid and blue in base

Ans . (b)

6. When soil becomes too basic, plants do not grow well in it. To improve its quality,

what must be added to the soil?

(a) Organic matter (b) Quick lime

(c) Slaked lime (d) Calamine solution
Ans. (a)

B. Fill in the blanks.

1. Curd contains .................... acid while vinegar contains .................... acid.

Ans. lactic, acetic

2. Phenolphthalein indicator turns acidic solutions to .................... and basic solutions

to .................... .
Ans. colourless, pink

3. The chemical name of lime water is ..................... .

Ans. calcium hydroxide

4. Bases are .................... in taste.

Ans. bitter
5. Acids are chemical substances which are .................... in taste and .................... in

nature.

Ans. sour, acidic

6. pH strips are pieces of paper that change colour depending on the .................... .

Ans. pH

49