## Tuesday, October 18, 2011

### Class 10 Science SA-II Paper (Set 1)

Class - X - SCIENCE (2011)
Time : 3 hours                                                                                              Maximum Marks : 80
SECTION - A
1. Name the part of the human eye that helps in changing the focal length of the eye lens.   (1)

2. Write the next higher homologue of the following :                                                              (1)
a. $C_3H_6$         b. $C_5H_8$
Answer: $C_4H_8 \text{ and } C_6H_10$ (more Q & A)

3. Select the biodegradable wastes from the following :
DDT, Crop’s residue, Leather and glass                (1)

4. In a food chain consisting of snake, insect, grass and frog, assign an appropriate
trophic level to frog.(1)
Answer: grass <--  insect  <-- frog <--- snake
Frogs are placed at Secondary Consumers trophic level. (See chapter notes)

5. What is the cause of dispersion of white light passing through a prism ?  Which colour
of light deviates the -
(i) most              (ii) least.              (2)
Answer: Angle of deviation is different for different colours of light. See at Chapter Notes.

6. Why does the clear sky appear blue ? How would the sky appear in the absence of  the earths atmosphere? (2)

7. How can you identify the three types of mirrors without touching ?                                     2

8. An element has electronic configuration 2, 8, 3.    What is the atomic number of this to which (i) group and    (ii)  period this element belong ?

9. How does atomic size vary in a group from top to bottom and in a period from left to         2

10. Name those parts of a flower which serve the same function as the following do in the animal.
(i) Testis      (ii) Ovary      (iii)    Eggs    (iv)    Sperms
Answer: (i) Testis: Anther    (ii) Ovary: ovary    (iii) Eggs: ova   (iv) Sperms:pollen grains

11. What are fossil fuels ? How are they formed ?                                                                2

12. What is ozone ? How does it protect the organisms on the Earth ?                                   2
13. What are sexually transmitted diseases ?   Name an STD which damages the immune system of human body? (3)

14. A real image $\frac{1}{5}th$ the size of object is formed at a distance of 18 cm from a mirror.What is the nature of the mirror? Calculate its focal length. (3)

15. A ray of light is incident obliquely on a glass slab. Draw a ray - diagram showing the path of the light ray. Clearly mark angle of incidence, angle of refraction, angle of  emergence and lateral displacement of the ray. Give a formula to find refractive index of glass slab in terms of angle of incidence and angle of refraction.   (3)

16. A person cannot see objects farther than 12m from the eye clearly. Name the,  defect of vision he is suffering from and the lens that should be used for correction of this defect. Illustrate with the help of a diagrams, how this lens will correct the defective vision. (3)

17. Give reasons for the following :                                                                                       3
(a) Unsaturated  hydrocarbons  show  addition  reactions  but  not  saturated hydrocarbons.
 (b) Carbon only forms covalent compounds. 18. State modern periodic law. Mention the position of (i) hydrogen and (ii) isotopes of same element in the modern periodic table. (3) 19. Distinguish between analogous organs and homologous organs.                                        3       Identify the analogous and homologous organs amongst the following:       (i) wings of the insect                        (ii) wings of a bat       (iii) forelimbs of frog                         (iv) forelimbs of human.