CBSE Board Class 10 Chemistry Sample Papers 2010

SAMPLE PAPER - 2010
CHEMISTRY
CLASS 10

1. The reaction of a metal ‘X’ with Fe2 O3 is highly exothermic and is used to join railway tracks. Identify the metal ‘X’ and write the chemical equation of its reaction with Fe2 O3.


2. Name the metals present in solder.


3. Doctors use a paste of a white substance in water to keep the fractured bone fixed in its place. Identify the substance and write its chemical formula.


4. (a) Write an expression of the law of chemical equilibrium for the following hypothetical reaction:

½ X+ 3Y ——-> 2Z

(b) What does the magnitude of equilibrium constant (K) indicate?
(c) For the reaction

N2 (g) + 3H2 (g) ——–> 2N H3 (g)

express the rate of reaction in terms of :-
[N2] [H2]  [NH3]
——, -,—— and ————
 t  t  t


5. How is soda glass prepared? What is the major disadvantage of using this glass?


6. Name the process that is used for the concentration of sulphide ores. Briefly describe this process.


7. (a) What are aldehydes and ketones? Name the functional group present in these compounds.
(b) Write the names of two reagents which can be used to distinguish between methanal and propanone.


8. (a) Write two tests to demonstrate that ethanoic acid (CH3COOH) is acidic in nature.
(b) Explain why are detergents more effective cleansing agents than soaps in hard water.


9. (a) Ammonia is manufactured from N2 and H2 by Haber process. State the
(i) Temperature, (ii) pressure, and (iii) the catalyst used in the process.
(b) What would you observe when ammonium hydroxide is added slowly to copper (II) sulphate solution until it is in excess. Write the chemical reactions that take place.


10. (a) The following flow chart represents the extraction of iron;

Iron Ore — Slag

Coke ——-
——-> Blast furnace ——>
A ——-
Iron
B —-

(i) Give the name of the iron ore.
(ii) Give the names of the substances A and B.
(iii) Write down the molecular formula of the slag formed.
(iv) What is the main impurity present in iron obtained from the blastfurnace.
(v) Name the chemical process that is used to obtain iron from iron ore.
(b) During the extraction of metals from their ores, the sulphide ores are roasted whereas the carbonate ores are calcined to obtain the oxide of the metal.
(i) Write an equation for the roasting of the zinc ore.
(ii) Write an equation for the calcination of the zinc ore.


Or

(a) The electronic configuration of an element ‘X’ is 2, 8, 6. It occurs in nature both in the combined state as well as in the free state. This element is mined by Frasch process. Answer the following questions.
(i) What is the name of the element ‘X’?
(ii) How many valencies are exhibited by this element? Write those valencies.
(iii) On which property of element ‘X’, the Frasch process is based?
(b) Describe briefly with the help of a labelled diagram the extraction of’X’ by Frasch process.