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Atoms — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsAtoms1 Mark
Question
For question two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is NOT the correct explanation of A.
  3. A is true, but R is false.
  4. A is false and R is also false.
Assertion (A): Smoky flame of Bunsen burner gives continuous spectrum whereas its blue flame gives band spectrum.
Reason (R): The band spectrum consists of coloured bands of light on a dark background.
✓

Answer

  1. Both A and R are true, but R is NOT the correct explanation of A.
Explanation:

When the flame of Bunsen burner is smoky, the carbon particles in it are in the incandescent state. Hence, the flame gives a continuous spectrum. But when the Burner gives a blue flame, then it has carbon, cynogen etc., in the molecular state. Hence, it gives band spectrum.

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