CBSE 10th Board Guess Paper Science Chemical reactions and equations, Electricity

Sample papers

Central Board of Secondary Education (CBSE)

Sample Paper – 2012
Class – X
Subject –
Topic – Chemical reactions and equations, electricity


1. What are oxidizing agents?

2. Give the formula of rust?

3. What type of reaction is     2K + CI             2KCI

4. What is SI unit of resistivity ?

5. Write the relationship among V,I and R ?

6. How is ammeter connected in a circuit ?

7. What are the advantages of connecting electrical devices in parallel whit the battery instead of connecting them in series ?
8. On what factors does the resistance of a conductor depend ?
9. Why are coils of electric toasters and electric irons are made of an alloy rather than a pure metal ?
10. Why should a magnesium ribbon be cleaned burning in air ?
11. A solution of a substance ‘ X ‘ is used for white washing.

(1) Name the substance ‘ X ‘ and write its formula.

(2) Write the reaction of the substance ‘ X ‘ named in (i) above with water.
12. Explain your view about the resistance in series.

13. Why we say combination is opposite of decomposition reaction? Explain with suitable example.
14. What is difference between displacement and double displacement reaction.
15. Calculate the equivalent resistance between A and B.


16. Can oxidation and reduction takes place alone. Explain with suitable examples.
17. (A)Mention the balanced equation for following:

(a) Liquid hydrogen peroxide decomposes to form water and oxygen gas.

(b) Sodium hydroxide reacts with sulphuric acid to form sodium sulphate and water

(c) Zinc metal reacts with aqueous hydrochloric acid to produce a solution of zinc chloride and hydrogen gas

(B) What is rancidity? Write the methods to prevent it.
18. (a) State and explain ohm’s law.

(b) What is power? Write its SI unit.

(c) State joules law of heating.
19.’Ampere’ is Si unit of :

(a) charge                               (b) current                               (c)potential                             (d) power
20.Instrument used to maintain constant potential difference is:

(a) ammeter                           (b) voltmeter                           (c) rheostat                             (d) battery
21. Loss of hydrogen and gain of oxygen is called:

(a0 oxidation                           (b)reduction                            (c) corrosion                            (d) none of these
22.Which of the following metal is protected by a layer of its oxide?

(a) copper                               (b) silver                                  (c) iron                                                (d) aluminium
23.Volt/ampere represents :

(a) ohm                                   9b) watt                                   (c) ampere                              (d) volt
24.volt x ampere represents:

9a) ohm                                   (b) watt                                   (c)volt                                      (d)ampere
25. Which of the following relation is not correct:

(a) P = VI                                 (b) I = V/R                                (c) R = VI                                 (d) P = IR

26. For which option Resistance is low:

(a) metals                                (b) non metals                         (c) alloys                                  (d) none of these

27.Decomposition AgBr generally requires :

(a) thermal energy                 (b) light energy                       (c) electric energy                  (d)none of these

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