Question

A hydrogen atom is in 5^th excited state. When the electron jumps to ground state, the velocity of recoiling hydrogen atom is –

• A. 1.1 m/s
• B. 4.2 m/s
• C. 8.4 m/s
• D. 11.2 m/s

Answer 1

Answer: (B)

4.2 m/s

Answer 2

DE = 13.6 $\left( \frac{1}{1^{2}} - \frac{1}{6^{2}} \right)$

= 13.22 eV

p = $\frac{\Delta E}{c}$

Ž v = $\frac{\Delta E}{mC}$= $\frac{13.22 \times 1.6 \times 10^{–19}}{1.67 \times 10^{–27} \times 3 \times 10^{8}}$

= 4.2 m/s