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Class 10
Chapter 1 Class 10 - Chemical Reactions and Equations

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.





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. 



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

So, the correct answer is (c)

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CA Maninder Singh is a Chartered Accountant for the past 13 years and a teacher from the past 17 years. He teaches Science, Economics, Accounting and English at Teachoo