Question

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

• A. $ 1.4\,kJ $
• 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 $=N h \frac{c}{\lambda}$
$N =6.02 \times 10^{23}$
$c=3 \times 10^{8}$
$\lambda =854\, \mathring{A}=854 \times 10^{-10} M$
$=\frac{6.02 \times 10^{23} \times 6.6 \times 10^{-34} \times 3 \times 10^{8}}{854 \times 10^{-10}}$
$=1.4 \times 10^{6} J\, mol ^{-1}$
$=1.4 \times 10^{3} kJ\, mol ^{-1}$