307138 If the energy of an electron in the second Bohr orbit of H-atom is −E , what is the energy of the electron in the Bohr's first orbit ?
We know that,En=−1312n2kJmol−1Given,E2=−131222⇒−13124=−E(1)∴E1=−131212(2)Comparing(1)in(2),weget,E14=−E∴E1=−4E
307170 The ionisation energy of a hydrogen atom is 13.6 eV. The energy of the third-lowest electronic level in doubly ionised lithium ion (Z=3) is
En=−I.E.n2Z2=−13.69×9eV=−13.6eV
307139 Based on the equation:ΔE=−2.0×10−18J(1n12−1n22), the wavelength of the light that must be absorbed to excite hydrogen electron from level n=1 to level n=2 will be:(h=6.625×10−34Js,c=3×108ms−1)
ΔE=−2.0×10−18×(122−112)=−2.0×10−18×−34=1.5×10−18ΔE=hcλλ=hcΔE=6.6×10−34×3×1081.5×10−18=1.325×10−7m
307140 If potential energy of an electron in hydrogen atom is −xeV, then its kinetic energy will be
K.E.=−12(P.E.)=x2eV
