SCIENCE AND TECHNOLOGY—2004 (Set III— Compartment Outside Delhi)

Except for the following questions, all the remaining questions have been asked in Set I and Set II.

Q. 2. What is the power of a concave lens of focal length 25 cm? 1

Q. 3. Write the name and chemical formula of the organic compound which is mixed in small quantities with ethanol to prepare denatured spirit. 1

Q. 6. What is meant by the term, ‘destructive distillation of wood’? Name any two products obtained during destructive distillation of wood. 2

Q. 7. Calculate the amount of charge that would flow in 1 hour through the element of an electric iron drawing a current of 0.4 A. 2

Q. 10. What are ‘shooting stars’? When do they become visible to .us? What are they called if they survive to reach the surface of the earth? 2

Q. 14. Find the position, nature and size of the image formed by a convex lens of focal length 20 cm of an object 4 cm high placed at a distance 30 cm from it. 3
Find the position, nature and size of the image of an object 3 cm high placed at a distance 6 cm from a concave mirror of focal length 12 cm.

Q. 15. Draw the pattern of field lines due to a solenoid carrying electric current. Mark the north and south poles in the diagram. 3
Draw a labelled diagram of a dry cell. Why should dry cells be used intermittently?

Q. 16. For a neutral solution at 298 K, what is
a) the pH.
b) hydrogen ion concentration of the solution?
The pH of a solution is changed from 3 to 5. By what factor would the concentration of its hydrogen ions change? 3

Q. 20. State Ohm’s law. Express it mathematically. Define SI unit of resistance. Derive an expression for the equivalent resistance of three resistors R1, R2 and R3 connected in series. 5

Q. 21. State any two characteristics of homologous chromosomes. 1

Q. 22. Name the scientist who proposed the theory of natural selection. 1

Q. 29. Write two main functions of excretion in living beings. Describe how excretion takes place in amoeba. 3