Question

If v1, v2, v3 and v4 are velocities of the electron
present in the first orbit of H, He+, Li+2 and Be+3,
then which of the following should be their increasing
order?
(a) v1 < v2 < v3 < v4
(b) v4 > v3 > v2 > v1
(c) v1 < v2 < v3 > v4
(d) v1 > v2 < v3 > v4

Answer 1

Answer:

b

Explanation:

in all cases no. of electron are same. according to atomic model V proportional to Z and inversely proportional to n where no. of orbit(n) are same for all cases but value of Z different.

Answer 2

Answer:

V1=V2=V3=V4

Explanation:

The Velocity of an electron present in an orbit is (2.18×10^8 Z /n) cm/sec where Z is the atomic number and n is the number of the orbital.

In the case of Hydrogen 1st orbit,

Velocity of H 1st orbit = 2.18×10^8×1/1  = 2.18×10^8 cm/sec

In the case of the Helium 2nd orbit,

Velocity of He 2nd orbit = 2.18×10^8×2/2  = 2.18×10^8 cm/sec

In the case of Li 3rd orbit,

Velocity of Li 3rd orbit = 2.18×10^8×3/3  = 2.18×10^8 cm/sec

In the case of Be 4th orbit,

Velocity of Be 4th or bit = 2.18×10^8×4/4  = 2.18×10^8 cm/sec

∴V1=V2=V3=V4