Assertion (A): After white washing the walls, a shiny white finish on walls is obtained after two to  three days.  

Reason (R): Calcium oxide reacts with carbon  dioxide to form calcium hydrogen carbonate  which gives a shiny white finish.  

 

Directions: In the following questions, a statement  of assertion (A) is followed by a statement of  reason (R). Mark the correct choice as:   

(a) Both assertion (A) and reason (R) are true and  reason (R) is the correct explanation of assertion  (A).  

(b) Both assertion (A) and reason (R) are true but  reason (R) is not the correct explanation of  assertion (A).  

(c) Assertion (A) is true but reason (R) is false.  

(d) Assertion (A) is false but reason (R) is true.

 

 

Answer 

Whitewash-01.jpg

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Calcium hydroxide is present in whitewash. 

It reacts slowly with the carbon dioxide  in air to form a thin layer of calcium carbonate on the walls. 

 

Calcium carbonate is formed after two to three days of white washing. Hence the shiny white finish appears after two to three days on the walls. 

 

Thus,

  • Assertion is true
  • Reasoning is false , as Calcium Carbonate is formed, not Calcium Hydrogen Carbonate

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So, the correct answer is (c)

  1. Class 10
  2. Chapter 1 Class 10 - Chemical Reactions and Equations (Term 1)

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Class 10
Chapter 1 Class 10 - Chemical Reactions and Equations (Term 1)

About the Author

CA Maninder Singh's photo - Founder at Teachoo
CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 11 years and a teacher from the past 11 years. He teaches Science, Accounts and English at Teachoo