Question

The ionization enthalpy of hydrogen atom is $1.312 xx 10^6 J mol^-1$. The energy required to excite the electron in the atom from $n= 1$ to $n = 2$ is :
A. $9.84xx10^(5) J "mol"^(-1)$
B. $8.51xx10^(5) J "mol"^(-1)$
C. $6.56xx10^(5) J "mol"^(-1)$
D. $7.56xx10^(5) J "mol"^(-1)$

Answer 1

Correct Answer - A
$IE=E(oo)-E(1)$
$E(1)=zero-IE(1)=-1.312xx10^(6)"J mol"^(-1)$.
$E(2)=(-1.312xx10^(6))/((2)^(2))=(-1.312xx10^(6))/(4)$
$=-1.312xx10^(6)$
$DeltaE=E(2)-E_(1)=-1.312xx10^(6)((1)/(4)-1)$
$=(-1.312)xx(-0.75)xx10^(6)$
$=9.84xx10^(5)"J mol"^(-1)$.