266. Which of the following compounds of zine is white when cold and yellow when hot ?

1. 1. ZnS

   
   
   

   2. ZnCl₂

   
   
   

   3. ZnSO₄

   
   
   

   4. ZnO

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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267. A metal gives two cholrides A and B. A give black ppt with NH₃ and B gives white, With Kl, B gives a yellow ppt, which is soluble in excess of Kl, A and B are respectively

1. 1. Hg₂Cl₂, HgCl₂

   
   
   

   2. HgCl, Hg₂Cl₂

   
   
   

   3. ZnCl₂, HgCl₂

   
   
   

   4. HgCl₂, ZnCl₂

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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268. Merscuric sulphide dissolves in aqua-regia to from

1. 1. Hg₂Cl₂

   
   
   

   2. HgCl₂

   
   
   

   3. Hg(NO₃)Cl

   
   
   

   4. Hg₂ (NO₃)₂

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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269. Consider the following statements :
     The purpose of adding sodium sulphate and sodium silicate to the detergent in a washing powder is
     1. to keep the washing powder dry
     2. to maintain the alkalinity of the powder
     Which of these statements is/are correct ?

1. 1. Only 1

   
   
   

   2. Only 2

   
   
   

   3. Both 1 and 2

   
   
   

   4. Neither 1 nor 2

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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270. Salts of which of the following elements provide colours to fireworks ?

1. 1. Zinc and sulphur

   
   
   

   2. Potassium and mercury

   
   
   

   3. Strontium and barium

   
   
   

   4. Chromium and nickel

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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