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CBSE - X
CBSEX-2005
Time allowed: 3 hours; Maximum Marks: 75
| General Instructions: | |
| 1) | The question paper comprises two Sections, A and B. You are to attempt both the Sections. |
| 2) | The candidates are advised to attempt all the questions of Section A separately and Section B separately. |
| 3) | All questions are compulsory. |
| 4) | There is no overall choice. However, internal choice has been provided in some questions. You are to attempt only one option in such questions. |
| 5) | Marks allocated to every question are indicated against it. |
| 6) | Question numbers 1—4 in Section A and 17— 18 in Section B are very short answer questions and are of 1 mark each. These are to be answered in one word or one sentence each. |
| 7) | Question numbers 5—8 in Section A and 19— 20 in Section B are short answer questions and are of 2 marks each. These are to be answered in 30—40 words each. |
| 8) | Question numbers 9—14 in Section A and 21—23 in Section B are also short answer questions and are of 3 marks each. These are to be answered in 40—50 words each. |
| 9) | Question numbers 15—16 in Section A and 24 in Section B are long answer questions and are of 5 marks each. These are to be answered in 70 words each. |
SECTION A
Question 1
1. Biological reactions in our body depend on the presence of biocatalysts.
What name is given to these catalysts? How is their activity influenced by changes in temperature?
Question 2
2. Name two metals both of which are very ductile as well as very
malleable.
Question 3
3. Write the chemical equation to represent the reaction taking place when copper oxide is heated in a stream of hydrogen.
Question 4
4. What are the values of (i) the angle of incidence, and (ii) the angle of reflection for normal incidence on a plane mirror surface?
Question 5
5. A wire of resistance 10 ohm is bent in the form of a closed circle. What is the effective resistance between the two points at the ends of any diameter of the circle?
Question 6
6. What happens when crystals of washing soda are left open in dry air? What is this change named as? Name two industries based on use of washing soda.
Question 7
7. "Sulphuric acid is a dibasic acid." Write two reaction equations to justify this statement and name the reaction products in the two cases.
Question 8
8. Explain the principle involved in the launching of artificial satellites.
Question 9
9.Light enters from air into a glass plate which has a refractive index of 1.50. Calculate the speed of light in glass. The speed of light in air is 3.0 x 108 m/s.
Question 10
10. Distinguish between 'prompt', 'delayed' and 'spontaneous' fissions of nuclei.
(OR)
Define a 'nuclear fusion reaction'. Describe the conditions for the occurrence of a nuclear fusion reaction.
Question 11
11. When does a reversible chemical reaction reach a state of equilibrium? Write the expression for the equilibrium constant (K) for the equilibrium reaction.
Question 12
12. Describe the 'steam reforming process' of manufacture of hydrogen from natural gas with the help of necessary chemical equations.
Question 13
13. Give the name and formula of the monomer of natural rubber. Why is natural rubber vulcanized? Write two uses of vulcanized rubber.
Question 14
14.(a) Write the
chemical equation representing the preparation reaction of ethanol from
ethane. (Out of syllabus)
(b) Name the product obtained when ethanol is oxidized by either chromic
anhydride or alkaline potassium permanganate,
(c) Give an example of an esterification reaction.
Question 15
15. If a 12 V battery is connected to the
arrangement of resistances given below, calculate
(i) the total effective resistance of the arrangement and
(ii) The total current flowing in the circuit.
| Section A | Section B |
