Tuesday, September 18, 2012


General Instructions:
i). The question paper comprises of two sections, A and B.  You are to attempt both the sections.
ii). All questions are compulsory.
iii). There is no overall choice.  However, internal choice has been provided in all the five questions of
five marks category.  Only one option in such questions is to be attempted.
iv). Questions 1 to 4 in section A are one mark questions.  These are to be answered in one word or
one sentence.
v). Questions 5 to 13 in section A are two marks questions.  These are to be answered in about 30
words each.
vi). Questions 14 to 22 in section A are three marks questions.  These are to be answered in about 50
words each.
vii). Questions 23 to 25 in section A are five marks questions.  These are to be answered in about 70
words each.
1. Give an example of an exothermic reaction.
2. Write electronic configuration of an element having atomic number 11.
3. Two resistors of 20 W and 40 W  are connected in parallel in an electric circuit. How  does the current passing through the two resistors compare ?
4. State the main function of abscisic acid in plants.
5.Oxidation and reduction processes occur simultaneously. Justify this statement with the help of an example.
6.Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate
(i)Translate the above statement into a chemical equation.
(ii) State two types in which this reaction can be classified.
7. Write the chemical name and formula of bleaching powder. How is it prepared ?
8. Give reason for the following :
(a) Ionic compounds have usually high melting and boiling points.
(b) Metals are good conductors of electricity whereas nonmetals are not.
9. State the factors on which the resistance of a cylindrical conductor depends. How will resistance of a conductor change if it is stretched so that its length is doubled ?
10.  In an experiment to study the relationship between the potential defference across a resistor and the current through it a student recorded the following observations :
Potential difference (V)          2          3                4.5            5          6
Current (A)                            0.08       0.12          0.15       0.20     0.24
Find in which one of the above sets of reading the trend is different from others and must be rejected. Calculate the mean value of resistance of the resistor based on the remaining sets of readings.
11. What is a solenoid ? Draw the pattern of magnetic field lines of a solenoid through which a steady current flows.
12.  How do guard cells regulate opening and closing of stomatal pores ?  13.
13. State the role of the brain in reflex action.
14. Design an activity to show a decomposition reaction in which light is used to decompose  a reactant. Write chemical equation of the reaction and state its one use.
15. What compound is Plaster of Paris ? How is it prepared ? What happens when it is mixed with water and allowed to stand ? Mention two applications of this property of Plaster of Paris.
16.  Five solutions A, B, C, D and E when tested with universal indicator showed pH as 4, 1, 11, 7 and 9 respectively. Which solution is (a) neutral (b) strongly alkaline (c) strongly acidic (d) weakly acidic and (e) weakly alkaline.
Arrange the pH in increasing order of Hion concentration.
17. Define electric current and state its SI unit. With the help of Ohms law explain the meaning of 1 Ohm resistance
18. The rating of an electric heater is 1100W; 220V. Calculate its resistance when it operates at 220V. Also calculate the energy consumed in  kWh in the month of November if the heater is used daily for four hours at the rated voltage.
19. An air conditioner of rating 2000W; 220V is operated in a domestic circuit (220V) that has a current rating of 5A. What result do you expect ? Justify your answer.
20. Draw a neat diagram to show structure of neuron and label on it the following :
cell body, axon, dendrite
21. State in brief the process of harnessing kinetic enargy of the wind to do work. Mention any four limitations of harnessing wind energy on a large scale.
22. How is nuclear energy generated ? State in brief the process of utilizing this energy in the production of electricity. Mention the major hazard of nuclear power generation.
23. Describe in short an activity to (i) demonstrate the pattern of magnetic field lines around a straight current carrying conductor, and (ii) find the direction of magnetic field produced for a given direction of current in the conductor. Name and state the rule to find the direction of magnetic field associated with a current carrying conductor. Apply this rule to determine the direction of the magnetic field inside and outside a current carrying circular loop lying horizontally on a table. Assume that the current through the loop in anticlockwise
24. (a)  list two differences between calcinator and roasting.
(b) An element X burns in oxygen to form an electrovalent compond XO. State the compounds you expect will form if the element X is made to combine with (i) chlorine and (ii) sulphur. Mention the Chemical formula and nature of bond present in each case.
25. What are magnetic field lines ? How is the direction of a magnetic field at a point  determined ? Draw the magnetic field lines (including field directions) of the magnetic field  due to a circular coil of current. Name any two factors on which the magnitude of the  magnetic field due to this coil depends.

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