Question

The speed of electrons in the second orbit of Be³⁺ion will be –

• A. $\frac{c}{137}$
• B. $\frac{2c}{137}$
• C. $\frac{3c}{137}$
• D. $\frac{4c}{137}$

Answer 1

Answer: (B)

$\frac{2c}{137}$

Answer 2

v₁ = $\frac{c}{137}$ Ž v_n = v₁ × $\frac{Z}{n}$

where, Z = 4, n = 2

v_n = v₁ × $\frac{4}{2}$ = 2v₁ = $\frac{2c}{137}$