5 observation that you seen on your households about the chapter acid base and salt
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aglasem
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NCERT Class VII Science Chapter 5 Acids, Base and Salts
by Anand Meena November 6, 2014 13 min read
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NCERT Class VII Science Chapter 5 Acids, Base and Salts
National Council of Educational Research and Training (NCERT) Book for Class VII
Subject: Science
Chapter: Chapter 5 – Acids, Base and Salts
Class VII NCERT Science Text Book Chapter 5 Acids, Base and Salts is given below
We use in our daily life a large number of substances such as lemon, tamarind, common salt, sugar and vinegar. Do they have the same taste? Let us recall tastes of some edible substances listed in Table 5.1. If you have not tasted any of these substances taste it now and enter the result in Table 5.1.
CAUTION
1. Do not taste anything unless asked to do so.
2. Do not touch anything unless asked to do so.
Table 5.1
Substance Taste (sour/bitter/any other)
Lemon juice
Orange juice
Vinegar
Curd
Tamarind (imli)
Sugar
Common salt
Amla
Baking soda
Grapes
Unripe mango
You find that some of these substances taste sour, some taste bitter, some taste sweet and some taste salty.
5.1 ACIDS AND BASES
Curd, lemon juice, orange juice and vinegar taste sour. These substances taste sour because they contain acids. The chemical nature of such substances is acidic. The word acid comes from the Latin word acere which means sour. The acids in these substances are natural acids.
What about baking soda? Does it also taste sour? If not, what is its taste? Since, it does not taste sour it means, that it has no acids in it. It is bitter in taste. If you rub its solution between fingers, it feels soapy. Substances like these which are bitter in taste and feel soapy on touching are known as bases. The nature of such substances is said to be basic. If we cannot taste every substance, how do we find its nature?
Special type of substances are used to test whether a substance is acidic or basic. These substances are known as indicators. The indicators change their colour when added to a solution containing an acidic or a basic substance. Turmeric, litmus, china rose petals (Gudhal), etc., are some of the naturally occurring indicators.
Answer:
shampoo.,detergent, soap, lemon juice,raw mango