Class 7 Science - HARYANA
Exploring Substances: Acidic, Basic and Neutral
In the chapter 'Exploring Substances: Acidic, Basic and Neutral' from the Class 7 Haryana (BSEH) Science syllabus, students learn to classify various substances found in daily life based on their chemical nature. The chapter covers the definitions and properties of acids, bases, and neutral substances. It introduces natural indicators like litmus, turmeric, and China rose, which change color to indicate the nature of a substance. Furthermore, students study the crucial process of neutralization, where an acid and a base react to form salt and water, explaining practical applications like treating indigestion and ant stings, which are high-yield board exam topics.
Start Learning FreeKey Concepts
Acids
Substances that taste sour and turn blue litmus red. They contain hydrogen ions and are found in citrus fruits like lemons and oranges.
Bases
Substances that taste bitter, feel soapy to touch, and turn red litmus blue. Examples include baking soda and washing soda.
Indicators
Special substances used to test whether a substance is acidic or basic by changing their color in different mediums. Natural indicators include litmus, turmeric, and China rose.
Neutral Substances
Substances that are neither acidic nor basic and do not change the color of red or blue litmus paper. Pure water is a common example.
Neutralization Reaction
A chemical reaction between an acid and a base that results in the formation of salt, water, and heat.
Important Formulas
Board Exam Info
In the Haryana (BSEH) Class 7 Science exams, this chapter typically carries around 5 to 7 marks. Common question types include differentiating between acids and bases, naming natural indicators and their color changes, writing word equations for neutralization reactions, and practical application-based questions like treating ant stings or soil acidity.
Frequently Asked Questions
What is the color change of blue litmus paper in an acidic solution?
Blue litmus paper turns red when dipped in an acidic solution.
Why does taking an antacid help when we have acidity?
An antacid is basic in nature. When taken, it neutralizes the excess acid in our stomach and gives us relief from indigestion.
Is distilled water acidic, basic, or neutral?
Distilled water is neutral because it is neither acidic nor basic, and it shows no color change with litmus paper.
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