CBSE Sample paper ( Light refraction and reflection, Electricity, Acid base and salt, Reproduction, Preodic table, Carbon and its Compound, Chemical reaction and Equation, Life process)

 

1. A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image formed.  (3 Marks)

2. Draw the ray diagram in each case to show the position and nature of the image formed when the object is placed: (i) at the centre of curvature of a concave mirror (ii) between the pole P and focus F of a concave mirror (iii) in front of a convex mirror (iv) at 2F of a convex lens (v) in front of a concave lens (5Marks)

3. What is the nature of the image formed by a concave mirror if the magnification produced by the mirror is +3? (2 Marks)

4. “The refractive index of carbon disulphide is 1.63. What is the meaning of this statement in relation to speed of light? (1 Marks)

5. Between which two points related to a concave mirror should an object be placed to obtain on a screen an image twice the size of the object? (1 Marks)

6. A ray of light enters a rectangular glass slab of refractive index 1.5. It is found that the ray emerges from the opposite face of the slab without being displaced. If its speed in air is 3 x 10⁸ms-1 then what is its speed in glass? (3 Marks)

7. At what distance should an object be placed from a convex lens of focal length 18 cm to obtain an image at 24 cm from it on the other side. What will be the magnification produced in this case? (3Marks)

8. State the two laws of reflection of light. (2 Marks)

9. How much current will an electric bulb draw from 220 V source if the resistance of the bulb is 1200Ω? If in place of bulb, a heater of resistance 100 Ω is connected to the sources, calculate the current drawn by it. (2 Marks)

10. How can the valency of an element  be determined if its electronic configuration is known? What will be ‘ the valency of an element of atomic number 9 (nine)? (2 Marks)

11. In the periodic table, how does the tendency of atoms to lose electrons change on going from
(i) left to right across a period? (ii) Top to bottom in a group? (2Marks)

12. The atomic number of an element is 16. Predict
(a) the number of valence electrons in its atom (b) its valency (c) its group number
(d) whether it is a metal or a non- metal (e) the nature of oxide formed by it (f) the formula of its chloride (5 Marks)

13. One of the constituents of baking powder is sodium hydrogencarbonate, the other constituent is (a) hydrochloric acid (b) tartaric acid (c) acetic acid (d) sulphuric acid ( 1 Marks)

14. The pH of the gastric juices released during digestion is (a) less than7(b) more than7 (c) equal to7(d) equal to 0

15. Which of the following is acidic in nature? (a) Lime juice (b) Human blood (c) Lime water (d) Antacid

16. A molecule of ammonia (NH₃ ) has (a) only single bonds (b) only double bonds (c) only triple bonds (d) two double bonds and one single bond

 
17. The inner lining of stomach is protected by one of the following from hydrochloric acid.  Choose the correct one (a) Pepsin (b) Mucus (c) Salivary amylase (d) Bile

18. When air is blown from mouth into a test-tube containing lime water, the lime water turned milky due to the presence of (a) oxygen (b) carbon dioxide (c) nitrogen (d) water vapour

19. The correct sequence of reproductive stages seen in flowering plants is (a) gametes, zygote, embryo, seedling (b) zygote, gametes, embryo, seedling (c) seedling, embryo, zygote, gametes (d) gametes, embryo, zygote, seedling

 
20. Vegetative propagation refers to formation of new plants from (a) stem, roots and flowers (b) stem, roots and leaves (c) stem, flowers and fruits (d) stem, leaves and flowers

21. The laws of reflection hold good for (a) plane mirror only (b) concave mirror only (c) convex mirror only (d) all mirrors irrespective of their shape