Class 7 Science - MAHARASHTRA
Exploring Substances: Acidic, Basic and Neutral
In the Maharashtra State Board (MSBSHSE) Class 7 Science chapter 'Exploring Substances: Acidic, Basic and Neutral', students learn to classify everyday substances based on their chemical properties. The chapter introduces natural and synthetic indicators like litmus, turmeric, and China rose, which change colors to identify acids and bases. It also covers the crucial concept of neutralization, explaining how acids and bases react to form salt and water, which has many practical applications in daily life such as treating acidity in the stomach and soil management. Mastery of these concepts is essential for scoring well in school examinations.
Start Learning FreeKey Concepts
Acids
Substances that taste sour and turn blue litmus paper red. Examples include lemon juice, tamarind, and vinegar.
Bases
Substances that taste bitter, feel soapy to touch, and turn red litmus paper blue. Examples include baking soda, soap, and lime water.
Indicators
Special substances used to test whether a given substance is acidic or basic by changing color in their presence.
Neutralization
A chemical reaction between an acid and a base that produces salt, water, and heat, neutralizing each other's properties.
Neutral Substances
Substances that are neither acidic nor basic and do not change the color of litmus. Water and common salt solution are examples.
Important Formulas
Board Exam Info
This chapter typically carries around 4 to 6 marks in the Maharashtra (MSBSHSE) Science examinations. Common question types include defining indicators, differentiating between acids and bases, giving examples of neutralization in daily life, and fill-in-the-blanks or match-the-following based on color changes of indicators.
Frequently Asked Questions
What is an indicator and how does it work?
An indicator is a dye or natural substance that shows different colors in acidic and basic mediums, helping us identify the nature of a substance without tasting it.
Why does soil sometimes become acidic and how is it treated?
Excessive use of chemical fertilizers makes soil acidic. It is treated by adding basic substances like slaked lime or quicklime to neutralize the acidity.
Does a neutral solution change the color of litmus paper?
No, neutral substances do not change the color of either red or blue litmus paper because they have a balanced pH and are neither acidic nor basic.
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