The best estimates of the age of the earth comes from the studies of

A. angle of inclination of the earth

B. changes in radio-active minerals in it

C. period taken by Sun's light to reach the earth

D. artificial satellites revolving round the earth

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  1. Cosmic rays contain
  2. The planet that is known as earth's twin is
  3. The direction of heat flow between two objects depends on
  4. Thick brick walls are used in the construction or a cold storage because bricks
  5. Bats flying in the dark avoid obstacles because
  6. Why is nuclear fusion also known as thermonuclear reaction?
  7. A body has fallen from a height. Just before touching the pound it has
  8. The device for tracking and locating the position of a moving object in space is called
  9. A projectile is fired at an angle with the horizontal with a small velocity. Its horizontal range will…
  10. In which of the following will a piece of iron weigh most?
  11. A rheostat is used
  12. The hygrometer is an apparatus used for finding the
  13. Which physical quantity is measured in watts
  14. The air inside an electric, bulb is removed to prevent
  15. Formation of shadows can be explained by
  16. Nuclear fission process means
  17. When a whistling engine approaches a person standing on the platform, the frequency or the note
  18. The sun continuously produces an enormous amount of energy. This la due to
  19. The mode of travel of heat energy from the sun across the empty space beyond the earth's atmosphere…
  20. Rain drops acquire spherical shape due to
  21. A person cups his hand around the mouth when shouting. Why?
  22. The heat generated in a conductor carrying current is proportional to
  23. The Solar System lies near the edge of a galaxy known as
  24. When temperature decreases, resistance of metals to flow of electricity
  25. The phenomenon of spontaneous disintegration of certain heavy nuclei is termed
  26. To concentrate light on the defective teeth, the dentists use
  27. Which of the following has the highest refractive index?
  28. Chronometer la an instrument to measure
  29. Besides protons, the nucleus of an atom contains
  30. The device used to record the sound is