Hots question for cbsc class 10 chemistry

How will you test for a gas which is liberated when HCL reacts with an active metal? 

2.         What is baking powder? How does it make the cake soft and spongy? 

3.       What happens chemically when quick lime is added to water? 

4.        Name the gas evolved when dilute HCL reacts with Sodium hydrogen carbonate. How is it recognized?

5.       How can washing soda be obtained from baking soda? Name an industrial use of washing soda other than washing clothes.

6.       What is the difference between shop and detergent?

7.        Give reason for the following observations:

  (a) The element carbon forms a very large number of compounds.

  (b) Air holes of a gas burner have to be adjusted when the heated vessels get blackened by the flame.

        

 b. Write a chemical equation to represent what happens when hydrogen gas is passed through unsaturated hydrocarbons in the presence of nickel as a catalyst.

 9.  On warming it with ethanol in the presence of a few drops of concentrated sulphuric acid, a compound ‘Y’ with a sweet smell is formed. Name the compound Y

10.  Distinguish between esterification and saponification reactions of organic compounds.

11. What change in colour is observed when silver chloride is left exposed to sunlight? Also mention the type of chemical reaction.

12. Define a combination reaction. Give one example of an exothermic as well as combination reaction.

13. Give an example of combination, displacement reaction, double displacement reaction.

14.  Name the anode and cathode used in electrolytic refining of impure copper metal.

15.  Give reasons for the following:

          (i) Metals can be given different shapes according to our needs.

          (ii) Hydrogen is not evolved when a metal reacts with nitric acid.

16. Give reasons for the following: (i) Aluminium oxide is considered as an amphoteric oxide.

17.  Give reasons for the following: (i) Gold and silver are used for jewellery making.

18. Given below are some elements of the modern periodic table:

            ₄Be, ₉Fe,₁₄Si, ₁₉K, ₂₀Ca

            (i)Select the element that has one electron in the outermost shell and write its electronic configuration.

            (ii)Select two elements that belong to the same group. Give reason for you answer.

            (iii)Select two elements that belong to the same period. Which one of the two has bigger atomic size?

19. write a short notes on following consider the properties, uses, reaction

  a) Baking powder

  b) plaster of Paris

  c) washing soda

20. what is difference between roasting and calcination explain with an example 

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