Acids Bases and Salts | Worksheet Solution | Class 7

Worksheet solutions for chapter: Acids Bases and Salts for class 7 are provided below.

(1) What are acids and bases?

Ans- Acids are those substances which taste sour. The word acid comes from the Latin word acere which means sour.

Eg- Lemon, Curd, Tamarind etc.

The chemical nature of these substances is acidic.

 The substances which are bitter in taste and feel soapy on touching are known as bases. The nature of these substances is said to be basic.

Eg-  Baking soda.

(2) Give characteristics of litmus.

Ans- Characteristics of litmus are given below:

(i) It is a natural indicator extracted from lichens.

(ii)It has mauve colour in the distilled water.

(iii) It turns red when added to acidic solution and it turns blue when added to basic solution.

(iv)It is available in the form of solution or in the form of strips of paper. It is commonly known as red or blue litmus paper.

(3) Why does turmeric spot on clothes red when we wash it with detergent?

Ans- When we wash turmeric spot on clothes it turns red because turmeric turns red in basic solutions. Detergent is a basic solution.

(4) What is neutralisation?

Ans- The process in which an acid and a base neutralize each other and salt and water produce, is called neutralisation.

Acid + Base → Salt + Water (heat is evolved)

Hydrochloric acid (HCL) + Sodium hydroxide (NAOH) → Sodium chloride (NACL) + Water (H2O)

(5) What is the use of neutralization in soil treatment?

Ans- When soil is acidic it is treated by bases like quick lime or slaked lime (calcium hydroxide) to neutralized acidic effect. When soil is basic it is treated by organic matters which releases acids to neutralized basic effect.

(6) Fill in the blanks:

(i) The colour of phenolphthalein in acidic solution is …..

(ii) ……. when added to the acidic solution turns red.

(iii) …… is always evolved in the neutralization.

Ans- 

(i) The colour of phenolphthalein in acidic solution is colourless.

(ii)Blue litmus when added to the acidic solution turns red.

(iii)Heat is always evolved in the neutralization.

(7) Write ‘T’ if statement is true and write ‘F’ if statement is false.

(i) Lime Water is basic in nature.

(ii) Shampoo turns blue litmus paper red.

(iii) Water is acidic in nature. 

Ans- 

(i) Lime Water is basic in nature.  T

(ii) Shampoo turns blue litmus paper red.   F

(iii) Water is acidic in nature.  F

Choose correct answer.

(8) Tamarind is

(i) basic in nature.

(ii) acidic in nature. 

(iii) neutral in nature.

Ans- 

Tamarind is

(i) basic in nature.

(ii) acidic in nature. 

(iii) neutral in nature.

(9) China Rose is a/an

(i) indicator.

(ii) base.

(iii) acid.

Ans-

China Rose is a/an

(i) indicator.  

(ii) base.

(iii) acid.

(10) In neutralisation reaction a new substance is formed. This is

(i) salt 

(ii) acid

(iii) pepper

Ans-

In neutralisation reaction a new substance is formed. This is

(i) salt  

(ii) acid

(iii) pepper

 

Helping Topics

Differences between acids and bases

Effect of different solutions on red and blue litmus paper

Effect of different solutions on turmeric solution

Effect of china rose on different solution

Effect of  different solutions on different indicators 

 NCERT solutions Class 7