The speed of the electron in the first Bohr orbit of hydrogen is 2.18x10^6 m s^-1 and in general v = 2.18x10^6 Z/n m s^-1. Find the speed of the electron in the fifth orbit of Li^2+ in units of 10^6 m s^-1, to two decimals.

JEE Main levelNumerical answerDifficulty 2 of 3as026

The speed of the electron in the first Bohr orbit of hydrogen is $2.18 \times 1 0^{6} m s^{- 1}$ and in general $v = 2.18 \times 1 0^{6} Z / n m s^{- 1}$ . Find the speed of the electron in the fifth orbit of $Li X^{2 +}$ in units of $1 0^{6} m s^{- 1}$ , to two decimals.

Numerical answer type, answer in x 10^6 m/s, tolerance 0.01.

For Li2+, Z = 3 and n = 5: v = 2.18 x 3/5 = 1.308 x

1 0^{6}

m/s, which is 1.31.