Q18 of 39 Page 1

Give one example each of a chemical reaction characterised by:
(i) evolution of a gas
(ii) change in colour
(iii) formation of a precipitate
(iv) change in temperature
(v) change in state. (CBSE 2016)

(i) A reaction between zinc metal and sulphuric acid.

(ii) Reaction between citric acid and purple coloured potassium permanganate. (from purple to colourless).

(iii) The reaction between Potassium iodide and lead nitrate is characterized by the formation of a yellow precipitate of lead iodide.

(iv) The reaction between quick lime and water to form slaked lime is characterized by a change in temperature.

(v) Water and carbon dioxide are formed when the wax is burned. Wax is solid whereas products are liquid and gas.

More from this chapter

All 39 →
18

(a) In electrolysis of water, why is the volume of gas collected over one electrode double that of gas collected over the other electrode?

(b) (i) What is observed when a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube?


(ii) What type of reaction is this?


(iii) Write a balanced chemical equation to represent the above reaction. (2015)


 19

(a) What happens when an aqueous solution of sodium sulphate reacts with an aqueous solution of barium chloride? State the physical conditions of reactants in which reaction between them will not take place. Write the balanced chemical equation for the reaction and also mention the type of reaction.

(b) What changes in the colour of iron nails and copper sulphate solution do you observe after keeping the iron nails in copper sulphate solution for about half an hour? (2015)


 19

Observe the diagram given alongside and answer the following questions:


a. What do you observe when lead nitrate is heated?


b. Mention the two gases evolved equation for it.


c. Write the balanced chemical equation for it.


d. What is the type of chemical reaction called?


e. Give one more example of this type of reaction.(CBSE 2008)

 20

You are provided with two containers made up of copper and aluminium. You are also provided with solutions of dilute HCl, dilute HNO3, ZnCl2, and H2O. In which of the above containers these solutions can be kept? (CBSE  2008)