Question

A photon having a wavelength of $845\mathring{A}$, causes the ionisation of $N$ atom. What is the ionisation energy of $N$ ?

• A. $1.4kJ$
• B. $1.4\times 10^{4}kJ$
• C. $1.4\times 10^{2}kJ$
• D. $1.4\times 10^{3}kJ$

Answer 1

Answer: (D)

The ionization energy is the amount of energy required to take out most loosely bonded electron from isolated gaseous atom
$\therefore$ Ionization energy of nitrogen = energy of photon
Where $=Nh\frac{c}{\lambda }$
$N=6.02\times 10^{23}$
$c=3\times 10^8$
$\lambda =854\mathring{A}=854\times 10^{-10}M$
$=\frac{6.02\times 10^{23}\times 6.6\times 10^{-34}\times 3\times 10^8}{854\times 10^{-10}}$
$=1.4\times 10^{6}Jmo{l}^{-1}$
$=1.4\times 10^{3}kJmo{l}^{-1}$