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 from the options given below
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 from the options given below
- A.A is not correct but R is correct
- B.Both A and R are correct and R is the correct explanation of A
- C.Both A and R are correct but R is NOT the correct explanation of A
- D.A is correct but R is not correct
Show answer and solution
Correct option: A
Solution
The Assertion is wrong because alkali metals impart characteristic colours to an oxidizing flame (or simply "flame" — not specifically a "reducing flame"). The flame test works because the heat excites the valence electrons of alkali metal atoms to higher energy levels, and the characteristic colour is emitted when they return to the ground state — this works in a standard/oxidizing flame, not specifically a reducing flame. The Reason R is independently correct: alkali metals are indeed detected by the flame test (Li → crimson red, Na → golden yellow, K → lilac, etc.). Since A contains a factual error (specifying "reducing flame"), A is incorrect, while R stands as a correct statement.
[JEE Main 2023 · 25 Jan · Shift 2]