CBSE Guess paper class X 2008 science 2

Class - X

Time: 2½ Hrs. Section A Mm: 60

Q 1. Give one use of anhydrous calcium chloride. (1)

Q 2. Why is electrolysis of distill water is not possible. How it is made possible. (1)

Q 3. A student obtains resistance of 16Ω, 12Ω, 4Ω, 3Ω only by using two metallic resistances wires either separately or joined together. What is the value of each resistor? (1)

Q 4. Give a condition when Snell law fails. (1)

Q 5. Why is series arrangement not satisfied for domestic circuit? (1)

Q 6. A current through a horizontal power line flows east to west direction. What is the direction of magnetic field at a point directly below it? Which rule you will apply in this regard. (1)

Q 7. A drop of water is poured over a white powdery substance ‘J’. I was observed the ‘J’ turns in blue substance ‘K’.

(i) What is white powdery substance ‘J’?

(ii) What is blue coloured substance ‘K’ and give nature of ‘K’. Give equation to convert ‘K’ to ‘J’. (2)

Q 8. A nichrome wire has a resistance of 5Ω. Find the resistance of another nichrome wire, whose length is four times and area of cross section is three times the first wire. (2)

Q 9. What is meant by frequency of an alternate current?

What is its value in India?

Why is alternate current considered to be advantageous over direct current for long-range transmission of electric energy? (2)

Q 10. What is rainbow? How it is caused. (2)

Q 11. A compound ‘X’ gained importance as a important symbol in our struggle for freedom. This movement was popularly known as Mahatama Gandhi’s Dandi March. Compound ‘X’ was found to possess m.p. =1074K

(a) Identify the compound.

(b) Write the nature of chemical bond found in between atoms of this compound.

(c) Write any two physical properties other than its mp. & b.p. (3)

Q 12. Define Modern Periodic law. Who gave the concept of this law?

How does electronegativity of an element vary on moving from-?

(i) Left to right in a period.

(ii) From top to bottom in a group. (3)

Q 13. A straight copper conductor, whose ends are connected to a sensitive galvanometer, is moved up and down in a strong magnetic field.

(i) State your observations and name the phenomenon.

(ii) What is the nature of induced current generated in the conductor?

(iii) What kind of energy transformation takes place in the above experiment and name the scientist who done above experiment. (3)

Q 14. (a) Draw a flow chart to show steps involved in extraction of metals from ore.

(b) Draw a labeled diag showing action of steam on metals. (3)

Q 15. (a) A mirror forms 2 times real and inverted image when object is placed at a distance of 10 cm. At what distance should an object be placed so that image is 3 times virtual and erect?

(b) Define power of lens and write its S.I. unit (5)


Give reason for the following:

(i) The sky appears to be blue during daytime to a person on earth.

(ii) The sun appears circular during evening hours.

(iii) The stars appear to twinkle.

(iv) The planets do not twinkle.

(v) Danger signals are made of red colour.

Q 16.. (a) An organic compound ‘Y’ is commonly used in medicine such as tincture iodine, cough syrup and many tonics.

(i) Identify the compound ‘Y’.

(ii) How will you convert to ethene? Give reaction involved.

(b) People use a variety of method to wash clothes; usually after adding the soap, they ‘beat’; the clothes on a stone of beat it with a paddle, scrub with a brush of the mixture is agitated in a washing machine.

Why is agitation necessary to get clean clothes?

(c) Represent the formation of micelles with a well-labeled diagram.

(d) Give two difference between soap and detergent. (5)


(a) Write various steps used in nomenclature of organic compounds.

(b) Describe versatile nature of carbon.

(c) Give electron dot representation of benzene. What type of hydrocarbon it is.

Section – B

Q 17. Give an advantage of solar cell over windmill. (1)

Q 18. Name the type of reproduction in Leishmania. (1)

Q 19. When we eat something we like, our mouth ‘Waters’. What is the actual meaning of this statement? (1)

Q 20. (a) What is advantage of taking in of water by fish through their mouth and forcing it past the gills?

(b) Compare the intestinal length of herbivores and carnivores. (2)

Q 21. Give three common features in lungs & gills. (2)

Q 22. Give the function of thymus gland and pineal gland. (2)

Q 23. (a) What do you mean by Coliform?

(b) Why there is need to clean aquarium time to time. (2)

Q 24. Three friends went for fishing to a pond. The nearby farms have fresh, greenish, insect free peas. Will you suggest them to sit there or to go elsewhere? Support your answer with suitable reason. (2)

Q 25. Give principle of

(i) Solar cell

(ii) Wind mill

(iii) Geothermal energy. (3)

Q 26. Give two limitation of nerve impulse. How can our body over come this? (3)

Q 27. Answer the following by giving reason:

(i) Fossil furnishes the direct and most reliable evidence for evolution.

(ii) All organisms have many common features.

(iii) Tail of mice appears in next generation of it if its tail is cut down.

(iv) Artificial selection is beneficial.

(v) The population of red beetles disappeared and green coloured beetles population increased in each generation in spite of presence of predator like crows?


Draw diagram of female reproductive system in humans and mark the organs where fertilization and implantation takes place.

What happens if egg is not fertilized?

After fertilization, a tissue is formed called placenta; explain its structure and functions? (5)


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