Exploring Substances Acidic Basic and Neutral — Question 19

The complete flowchart is as follows:
Class 7 Exploring Substances Acidic Basic and Neutral Question Answer (Activities)
Activity 2.1: Let Us Explore (Page 8-9)
Table 2.1: Testing the nature of samples with blue and red litmus papers
Name of the Sample
Colour of blue litmus paper after putting a drop of sample
Colour of red litmus paper after putting a drop of sample
Lemon juice
Red
Red
Soap solution
Blue
Blue
Amla juice
Red
Red
Tamarind water
Red
Red
Vinegar
Red
Red
Baking soda solution
Blue
Blue
Lime water
Blue
Blue
Tap water
Blue
Red
Washing powder solution
Blue
Blue
Sugar solution
Blue
Red
Salt solution
Blue
Red
Orange juice
Red
Red
Table 2.2: Grouping of samples tested in Table 2.1
Group A
Group B
Group C
Lemon juice, Amla juice, Tamarind water, Vinegar, Orange juice
Soap solution, Baking soda solution, Lime water, Washing powder solution
Tap water, Sugar solution, Salt solution
Observation and conclusion: Substances in Group A, like lemon juice and vinegar, are acidic as they turn blue litmus paper red. Group B substances, like soap and baking soda, are basic as they turn red litmus paper blue. Group C substances, like tap water and sugar solution, are neutral because they do not change the litmus paper colour.
Activity 2.2: Let Us Relate and explore (Page 11)
All the substances in Group A – lemon juice, amla juice, tamarind water, vinegar and orange juice are edible. They all have a sour taste because they contain acids and are acidic in nature. The common acids found in these substances are:
Lemon: Citric acid
Curd: Lactic acid
Tamarind: Tartaric acid
Vinegar: Acetic acid
Activity 2.3: Let Us Prepare (Page 12)
Answer:
Do it yourself.
Activity 2.4: Let Us Find out (Pages 12-13)
Table 2.3: Testing the nature of samples with red rose extract
Name of the Sample
The colour of the red rose extract after adding the sample
Nature of substance
Lemon juice
Red
Acidic
Soap solution
Green
Basic
Amla juice
Red
Acidic
Baking soda solution
Green
Basic
Vinegar
Red
Acidic
Observation and conclusion: The rose extract gives a red colour in an acidic solution and a green colour in a basic solution.
Activity 2.5: Let Us Prepare (Pages 14-15)
Table 2.4: Testing the nature of samples with turmeric paper
Name of the Sample
The colour of the turmeric paper after putting a drop of sample
Lemon juice
Yellow
Soap solution
Red
Amla juice
Yellow
Baking, soda solution
Red
Sugar solution
Yellow
Observation and conclusion: Turmeric paper changes colour from yellow to red in a basic solution but shows no change in acidic or neutral solutions.
Activity 2.6: Let Us Lnvestigate (Page 16)
Answer:
Do it yourself.
Activity 2.7: Let Us Experiment (Page 17)
Answer:
Do it yourself.