Chemical reactions and equations class 10

1.Why is respiration considered an exothermic reaction ?

2.Why do copper vessel lose shine when exposed to air ?

3. Potato chips manufacturers fill the packet of chips with nitrogen gas.
Why ?

4. Why we store silver chloride in dark coloured bottles ?

5. Write a chemical equation of double displacement reaction.

6. What happens when milk is left open at room temperature during
summers ?

7. What happens when quick lime is added to water ?

8. Define combination reaction.

9. Give one example of combination
reaction which is exothermic in nature.

10 .What is decomposition reaction ? Explain with the help of an example.

11. Give one example of each:
(a) Chemical reaction showing evolution of gas.
(b) Change in substance’s colour during a chemical reaction.

12. What is rancidity ? Write two ways by which it can be prevented.

13. What are two conditions which promotes corrosion ?

14. _Asmall amount of ferrous sulphate is heated in hard glass tube.
(a) Write the chemical equation.
(b) What type of reaction is taking place.

15. What happens when Zn strip is dipped in CuSO, solution ?
1. Whatis redox reaction ? Write down a chemical reaction representing

16. _In electrolysis of water :
(a) Name the gas collected at cathode and anode.

(b) Why is volume of one gas collected at one electrode is double of
another ?

(c) Why are few drops of dil. H,SO, added to water ?

17.Give reasons :

(a) White silver chloride turns grey in sunlight.

(b) Brown coloured copper powder on heating in air turns into black
coloured substance.

18 .Write down the balanced chemical equation for the following :

(a) Silver chloride is decomposed in presence of sunlight to give
silver and chlorine gas.

(b) Calcium oxide reacts with water to give lime water.

(c) Sodium hydroxide reacts with hydrochloric acid to give
sodium chloride and water.

(d) Die hydrochloric acid is added to copper oxide to give green
coloured copper chloride and water.

(e) Solution of barium chloride and sodium sulphate in water
reacts to give insoluble barium sulphate and solution of sodium

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