Chem Mantra
HomeCoursesOnline TestsForum
ForumQuestion BankWhen sodium compounds are heated in a Bunsen bu…
HARDMCQ SINGLEJEE Advanced ChemistryPhysical ChemistryAtomic StructureIntro

When sodium compounds are heated in a Bunsen burner flame, they emit light at 5890 Å. If 1.0 × 10⁻⁴ moles of sodium atoms each emit one photon of this wavelength, how much energy (in kJ) is emitted?

0.2.03 × 10⁻² kJ
1.8.08 × 10⁻³ kJ
2.6.20 × 10⁻² kJ
3.2.03 × 10⁻³ kJ
Explanation

n = 10⁻⁴ × 6.023×10²³ = 6.023×10¹⁹ atoms. E = nhc/λ = (6.023×10¹⁹ × 6.626×10⁻³⁴ × 3×10⁸) / (5890×10⁻¹⁰) = 0.02031 kJ = 2.03×10⁻² kJ

Back to Question Bank

Practice More Like This

Take chapter-wise tests, track your progress, and master Atomic Structure.

Start Free Practice →
Sponsored

Master Chemistry for JEE, NEET & IChO

Access 19,000+ solved questions with expert explanations, chapter-wise tests, and full video lectures — all in one platform.

JEE Advanced Chemistry
Explore Courses →Sign In Free