Class 7 Science Acids Bases And Salts Worksheets

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Class 7 Science Acids Bases And Salts Worksheets

Are acids always sour? What happens when you mix a base with an acid? In Class 7 Science Acids Bases And Salts Worksheets, you’ll uncover the amazing world of acids, bases, and salts all around you—from lemon juice to soap! These worksheets are designed to explain the differences between them and teach you how they react with each other in simple, clear steps.

Many students get confused about indicators, neutralisation, and real-life uses of acids or bases—these worksheets clear up those doubts with loads of examples and easy exercises. You can also find the full syllabus as you prepare, helping you link each worksheet to what you’ll learn in school. Check the Class 7 Science Syllabus for more details on what’s covered in your course.

With Vedantu’s trusted resources and downloadable PDF worksheets, you can test your knowledge, practice key questions, and get ready for school exams the fun way. For more chapter-wise practice, don’t forget to visit the Class 7 Science Important Questions page.

Tips for passing the CBSE Class 7 Science test with flying colours:

A sound approach is regarded as a need for achieving a high score on the CBSE Class 7 Science test. Science is viewed as a competition of speed, precision, and practice. Here are some pointers for getting high grades:
Cover the entire curriculum. Despite the fact that the Science curriculum is rather long, students are advised to read it completely in order to be prepared for any queries that may arise.
Solve a variety of challenging and interesting problems. Science studies may be challenging for pupils since there are so many different sorts of questions that can be posed.
As many test series as feasible should be written. Test series and practice are the only tools that may help you prepare for the Class 6 Science examination. Aspirants should not be discouraged if their practice test scores are low.
Determine your weak points and practice extra hard on them.

FAQs on Class 7 Science Acids Bases And Salts Worksheets

1. What are some of the most frequently asked 3-mark questions from CBSE Class 7 Science Chapter 5, Acids, Bases, and Salts?

For the CBSE 2025-26 exams, important 3-mark questions from this chapter often focus on application and differentiation. Students should prepare for questions such as:

Distinguishing between acids and bases based on three key properties (e.g., taste, effect on litmus, and effect on turmeric).
Explaining the neutralisation reaction with a balanced chemical equation and a real-world example like treating indigestion.
Describing how to use China rose petals as a natural indicator to test acidic, basic, and neutral solutions.

2. A student is given three unlabelled test tubes: one with an acidic solution, one with a basic solution, and one with distilled water. How can they identify all three using only a strip of red litmus paper?

This is a classic HOTS (Higher Order Thinking Skills) question. The student can identify the solutions in three steps:

Step 1: Dip the red litmus paper into each of the three solutions. The solution that turns the red litmus paper blue is the base.
Step 2: Now, use this same litmus paper, which has turned blue, to test the other two solutions. The solution that turns this blue litmus paper back to red is the acid.
Step 3: The remaining solution, which did not cause any change to the litmus paper in either step, is the distilled water (neutral).

3. Why does a turmeric stain on a white shirt turn reddish-brown when scrubbed with soap? What is the scientific principle involved?

A turmeric stain turns reddish-brown when scrubbed with soap because soap is basic in nature. Turmeric acts as a natural indicator. It remains yellow in acidic and neutral substances but changes its colour to reddish-brown when it comes in contact with a base. This phenomenon is a practical demonstration of how indicators are used to identify the chemical nature of a substance.

4. How is the concept of neutralisation applied to treat an ant sting, and why is this an important question for exams?

This is an important application-based question. An ant sting injects formic acid into the skin, causing pain and irritation. To get relief, a mild base like baking soda (sodium hydrogen carbonate) or calamine solution (containing zinc carbonate) is applied. The base neutralises the effect of the acid on the skin. This is a perfect example of a neutralisation reaction in daily life, a core concept in the CBSE Class 7 syllabus for the 2025-26 session.

5. What are the key differences between acids and bases that a Class 7 student must know for their exam?

For the Class 7 exam, the following differences are crucial:

Taste: Acids are generally sour (like lemon juice), whereas bases are bitter (like baking soda).
Touch: Bases feel soapy to the touch, while acids do not.
Litmus Test: Acids turn blue litmus paper red. Bases turn red litmus paper blue.
Effect on Turmeric: Acids do not change the colour of turmeric, but bases turn it reddish-brown.

6. Why is it necessary to treat factory waste before releasing it into rivers, based on the principles of this chapter?

It is crucial to treat factory waste because it often contains harmful acids. If this acidic water is released directly into rivers, it can kill fish and other aquatic organisms, severely damaging the ecosystem. To prevent this, the factory waste is first treated with basic substances, such as slaked lime (calcium hydroxide). This process neutralises the harmful acids, making the waste safe for disposal into water bodies as per environmental safety regulations.

7. A common misconception is that all salts are neutral. Is this always true? Explain in the context of the Class 7 syllabus.

While the neutralisation reaction between an acid and a base produces a salt and water, it's a misconception that all salts are neutral. In Class 7, we primarily learn that a reaction like Hydrochloric acid (HCl) + Sodium hydroxide (NaOH) gives Sodium chloride (NaCl), a neutral salt. However, salts can also be acidic or basic depending on the strengths of the acid and base that create them. For the exam, it's important to know that the product of neutralisation is a salt, which is typically neutral in the examples provided in the NCERT textbook.