Acids, Bases and Salts Class 7 Science NCERT

Q. 1. State differences between acids and bases.

Q.2. Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. What is its nature?

Q.3. Name the source from which litmus solution is obtained. What is the use of this solution?

Q.4. Is the distilled water acidic/basic/neutral? How would you verify it?

Q.5 Describe the process of neutralization with the help of an example.

6. Mark ‘T’ if the statement is true and ‘F’ if it is false:

(i) Nitric acid turns red litmus blue. (T/F)

(ii) Sodium hydroxide turns blue litmus red. (T/F)

(iii) Sodium hydroxide and hydrochloric acid neutralize each other and form salt and water. (T/F)

(iv) Indicator is a substance which shows different colors in acidic and basic solutions. (T/F)

(v) Tooth decay is caused by the presence of a base. (T/F)

Q.7.Dorji has a few bottles of soft drinks in his restaurant. But, unfortunately, these are not labeled. He has to serve the drinks on the demand of customers. One customer wants an acidic drink, another wants a basic one and the third one wants a neutral drink. How will Dorji decide which drink is to be served to whom?

Q.8. Explain why:

(a) An antacid tablet is taken when you suffer from acidity.

(b) Calamine solution is applied on the skin when an ant bites.

(c) Factory waste is neutralized before disposing it into the water bodies.

Q. 9. Three liquids are given to you. One is hydrochloric acid, another is sodium hydroxide and the third is a sugar solution. How will you identify them? You have only a turmeric indicator.

Q. 10. Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.

Q.11. Consider the following statements:

(a) Both acids and bases change the color of all indicators.

(b) If an indicator gives a color change with an acid, it does not give a change with a base.

(c) If an indicator changes color with a base, it does not change color with an acid.

(d) Change of color in an acid and a base depends on the type of the indicator.

Which of these statements are correct?

(i) All four (ii) a and d (iii) b, c, and d (iv) only d

Q.8. Explain why:

(a) An antacid tablet is taken when you suffer from acidity.

(b) Calamine solution is applied on the skin when an ant bites.

(c) Factory waste is neutralized before disposing it into the water bodies.

Q. 9. Three liquids are given to you. One is hydrochloric acid, another is sodium hydroxide and the third is a sugar solution. How will you identify them? You have only a turmeric indicator.

Q. 10. Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.

Q.11. Consider the following statements:

(a) Both acids and bases change the color of all indicators.

(b) If an indicator gives a color change with an acid, it does not give a change with a base.

(c) If an indicator changes color with a base, it does not change color with an acid.

(d) Change of color in an acid and a base depends on the type of the indicator.

Which of these statements are correct?

(i) All four (ii) a and d (iii) b, c, and d (iv) only d