The electron in the first Bohr orbit of singly-ionised helium (He , ) moves with speed

CHEMISTRY · Single correct · CBSE · Chemistry · Structure of Atom · Structure of Atom

Problem

The electron in the first Bohr orbit of singly-ionised helium (He

^{+}

Z=2

) moves with speed

v_{\text{He}}

. The corresponding speed in the first Bohr orbit of hydrogen is

v_{\text{H}}

. Which one of the following relations is correct? (a)

v_{\text{He}} = v_{\text{H}}

(b)

v_{\text{He}} = \dfrac{v_{\text{H}}}{2}

(c)

v_{\text{He}} = 2\,v_{\text{H}}

(d)

v_{\text{He}} = 4\,v_{\text{H}}