Skip to content
dronacharya.ai
← JEE Main 2022 · 25 Jun · Shift 1
ChemistryInteger+4 / -1Question 83 of 90

JEE Main 2022 · 25 Jun · Shift 1, Chemistry question 83

The longest wavelength of light that can be used for the ionisation of lithium atom (Li) in its ground state is x×10−8x\times10^{-8} m. The value of xx is ______. (Nearest Integer)

(Given : Energy of the electron in the first shell of the hydrogen atom is −2.2×10−18-2.2\times10^{-18} J; h=6.63×10−34h=6.63\times10^{-34} Js and c=3×108 ms−1c=3\times10^8\ \mathrm{ms^{-1}})

Answer and worked solution

Official answer: 4

Ionisation energy (hydrogen-like, Li in n=2n=2, Z=3Z=3): E=2.2×10−18×94=4.95×10−18E=2.2\times10^{-18}\times\dfrac94=4.95\times10^{-18} J.

Wavelength. λ=hcE=6.63×10−34×3×1084.95×10−18≈4.0×10−8\lambda=\dfrac{hc}E=\dfrac{6.63\times10^{-34}\times3\times10^8}{4.95\times10^{-18}}\approx4.0\times10^{-8} m.

Answer: 4

Topics:Bohr model
← Previous questionNext question →