CBSE Guess Paper class X 2008 science 4

Guess Paper – 2008
Class – X
Subject – Science

TIME: Max Marks: 60

General Instructions:

a) The question paper comprises of two sections A and B. You are to attempt both the sections.

b) All questions are compulsory.

c) There is no overall choice. However, internal choice has been provided in all the three questions of five marks category. Only one option in such questions to be attempted.

d) All questions of section A and all questions of section B are to be attempted separately.

e) Questions 1 to 6 in section A and 17 to 19 in section B are short answer type questions and carry one mark each.

f) Questions 7 to 10 in section A and 20 to 24 in sections B are short answer type questions and carry two marks each.

g) Questions 11 to 14 in section A and 25 to 26 in section B are short answer type questions and carry one mark each.

h) Questions 15 and 16 in section A and 27 in section B are short answer type questions and carry one mark each.


1) A substance 'X' turns grey when kept in sunlight to form silver metal. It is used in black and white photography films. Identify the substance and type of reaction it undergoes.

2) An element 'X' reacts with oxygen to form acidic oxides and is also a good conductor of heat and electricity. Is element 'X' a metal or a non-metal? What happens when X reacts with an acid?

3) What is the chemical composition of Soap?

4) The following data represents the strength of magnetic field at different distances from a current carrying conductor.










One of the observations is wrong. Identify the observation and justify your answer.

5) A ray of light AFB is incident on a spherical mirror as shown in the diagram. Redraw the diagram on the answer sheet and show the path of the reflected ray. Also indicate and mark the angle of incidence.

6) Let the resistance of an electrical component remain constant while the potential difference across the two ends of the component decreases to half of its former value. What change will occur in the current through it? Name the unit of current.

7) What is a Redox reaction? Give one example. Identify the reducing and oxidizing agent.

8) What do you mean by the activity series of metals? On the basis of following reactions arrange the metals A,B &C in increasing order of reactivity:

9) You are given an ammeter, a voltmeter, a battery and three resistances of value 6Ω each. Draw a complete circuit diagram using these components to get equivalent resistance of 4 Ω.

10) Human eye is capable of focusing at objects placed at varying distances by adjusting the focal length of the eye lens. What is the name of this special property of the eye? An optician prescribed a lens of power +2.0D to a patient. Identify the nature of lens, its focal length, defect patient is suffering.

11) Study the placement of following elements in the periodic table and answer the questions given below:

























a. Which elements have the largest and the smallest atomic radii?

b. Which element will always form covalent compounds?

c. Which two elements have the valency 1?

d. Which element has the highest metallic and non-metallic character?

12) Answer the following questions:

a. Give one example of reaction of metal oxides with acids?

b. Why does tooth decay occur?

c. Which property of plaster of Paris makes it suitable for use in the hospitals? Give the reaction involved also.

13) What do you mean by Electromagnetic Induction? State the rule to find the direction of induced current.

14) What do you mean by Atmospheric refraction? Explain:

a. Formation of rainbow

b. Why sky appears blue?

15) An organic compound 'A' has molecular formula. 'A' reacts with sodium carbonate to liberate a gas which turns lime water milky. 'A' also reacts with a substance 'B' to form a sweet smelling substance 'C'. Substance 'A' is also used as a preservative for pickles and sauces.

a. Identify the compounds A, B & C.

b. Give the equations for:

i. Reaction of A with sodium carbonate.

ii. Reaction of A and B to form C.

c. How can A and B be obtained back from 'C'? What is the name given to this conversion reaction?


a. Give two reasons for the formation of a large number of compounds by a carbon atom? What do you mean by a functional group?

b. Identify the functional group and name the following carbon compounds:



c. What do you mean by Hydrogenation? Give its one use.

16) Answer the following questions:

a. Why tungsten is used almost exclusively as filament of electric lamps?

b. Why parallel arrangement is used for domestic circuits instead of series?

c. An electric refrigerator rated at 400W operates 8hrs/day. What is the cot of energy to operate it for 30 days at Rs3.00 per kWh?

d. Draw a diagram to depict magnetic field lines around a current carrying circular loop? List one factor on which the strength of magnetic field depends.


a. What do you mean by short circuiting and overloading?

b. Name the safety device used to prevent above conditions? What is it made up of?

c. Two lamps, one rated 100W at 220V, and the other 60W at 220V, are connected in parallel to electric mains supply. What current is drawn from the line if the supply voltage is 220V?

d. Draw a diagram to depict the magnetic field lines around a solenoid. List one factor on which the strength of magnetic field depends.


17) Name the reproductive organs in human beings for the release of: a) Sperms b) Ova.

18) Name two industries largely based on the forest products.

19) Name the hormone secreted by Pancreas to reduce the sugar level in the body, also name one digestive enzyme secreted by pancreas.

20) What type of reproduction occurs in Hydra? With the help of diagram show the reproduction in Hydra.

21) Name the parts of the brain responsible for controlling:

a. Heart beat and blood pressure.

b. Posture and movement of body.

c. Reflex action like size of pupil

d. Association of learning.

22) What is Biological Magnification? List any two substances which can cause Biological Magnification. Will the levels of magnification be different at different levels?

23) What do you mean by Sustainable Management? List one reason why we need to manage our resources. List any one instance where people participation helped in management of forests.

24) What do you mean by Water Harvesting? List two characteristic features of modes of water harvesting? List any two traditional methods and the areas they are practiced of water harvesting.

25) Show the monohybrid cross of Tall (TT) pea plan with a Dwarf (tt) pea plant, to generate and progeny. What will be the ratio of tall and dwarf plants in and progeny? Also give the Genotype of andprogeny.

26) Answer the following questions:

a. Why is top of solar cooker covered with a plane glass lid?

b. List two limitations of wind energy.

c. What are the two conditions necessary for the working of an OTEC system?

27) Draw a labeled diagram of Human Digestive system and highlight Liver, Pancreas and Rectum.

List one enzyme and its function secreted by Small Intestine and Liver.


Draw Respiratory System in Human beings and highlight Larynx, Trachea and Primary bronchus.

Explain the mechanism of breathing in human beings.


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