Q3 / 90 · JEE Main 2023 (25 Jan Shift 2) · Chemistry

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R

Assertion A:- The alkali metals and their salts impart characteristic colour to reducing flame.

Reason R:- Alkali metals can be detected using flame tests.

In the light of the above statements, choose the most appropriate answer form the options given below

  • A
    Both A and R are correct but R is NOT the correct explanation of A.
  • B
    A is correct but R is not correct.
  • Correct answer
    C
    A is not correct but R is correct
  • D
    Both A and R are correct and R is the correct explanation of A.

Solution

An assertion is incorrect because alkali metals and their salts impart characteristic colour to an oxidising part of the flame and not a reducing part of the flame. The heat from the flame excites the outermost orbital electron to a higher energy level. When the excited electron comes back to the ground state, there is an emission of radiation in the visible region.

Reason is correct because all alkali metals can be detected by their flame tests and can be determined by flame photometry or atomic absorption spectroscopy. 

Hence, the correct answer is option: 'C'.

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