Q. The first excited state of hydrogen atom is $10.2\ eV$ above its ground state. The temperature is needed to excite hydrogen atoms to first excited level, is
A) $7.9 \times 10^{4}\ K$
B) $3.5 \times 10^{4}\ K$
C) $5.8 \times 10^{4}\ K$
D) $14 \times 10^{4}\ K$
Explanation
(a) According to kinetic interpretation of temperature
$K.E. = \left( \frac{1}{2}mv^{2} \right) = \frac{3}{2}kT$
$\Rightarrow 10.2 \times 1.6 \times 10^{- 19} = \frac{3}{2} \times \left( 1.38 \times 10^{- 23} \right)T$
$\Rightarrow T = 7.9 \times 10^{4}K$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.