JEE Main 2021 — S Block Elements Question with Solution
From: JEE Main 2021 (Online) 24th February Evening Shift
Question
Match List - I with List - II.
Choose the correct answer from the options given below :
| List I (Salt) | List II (Flame colour wavelength) | ||
|---|---|---|---|
| (a) | LiCl | (i) | 455.5 nm |
| (b) | NaCl | (ii) | 670.8 nm |
| (c) | RbCl | (iii) | 780.0 nm |
| (d) | CsCl | (iv) | 589.2 nm |
Choose the correct answer from the options given below :
Choose an option
Show full solutionCorrect option: D
Correct answer
D(a)-(ii), (b)-(iv), (c)-(iii), (d)-(i)
Step-by-step explanation
| Alkali metal | Colour (Flame) | (nm) |
|---|---|---|
| Li | Crimson red | 670.8 |
| Na | Yellow | 589.2 |
| Rb | Red, violet | 780.0 |
| Cs | Blue | 455.5 |
Alkali metals have very low value of ionisation energy as compared to other metals. So, alkali metals easily get excited and impart colour to flame.
Hence, Rb is most excited and having high value of wavelength in all alkali metals.
Practice this on the real CBT interface
Solve this JEE Main question (and the rest of the S Block Elements chapter) on PrepSharp's TCS iON-style CBT player — with timer, bookmarks and session analytics.
Solve interactively →About this question
This is a previous-year question from JEE Main 2021, covering the S Block Elements chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.