For the ground state, the electron in the H-atom has an angular momentum = h, according to the simple Bohr model. Angular momentum is a vector and hence ….

Q: For the ground state, the electron in the H-atom has an angular momentum = h, according to the simple Bohr model. Angular momentum is a vector and hence there will be infinitely many orbits with the vector pointing in all possible directions. In actuality, this is not true,

(a) because Bohr model gives incorrect values of angular momentum

(b) because only one of these would have a minimum energy

(c) angular momentum must be in the direction of spin of electron

(d) because electrons go around only in horizontal orbits

Ans: (a)

In a Rutherford scattering experiment when a projectile of z1 and mass M1 approaches a target nucleus of charge z2 and mass M2. The distance of closest approach is r_0. The energy of the projectile is

Q: In a Rutherford scattering experiment when a projectile of z1 and mass M1 approaches a target nucleus of charge z2 and mass M2. The distance of closest approach is r0 . The energy of the projectile is

(a) Directly proportional to M1 × M2

(b) Directly proportional to z1z2

(c) Inversely proportional to z1

(d) Directly proportional to mass M1

Ans: (b)

Sol: $\large \frac{1}{2}M_1 v^2 = \frac{1}{4\pi \epsilon_0} \frac{(Z_1 e)(Z_2 e)}{r_0}$

Where r0 = distance of closest approach

$\large r_0 = \frac{1}{4\pi \epsilon_0} \frac{(Z_1 e)(Z_2 e)}{\frac{1}{2}M_1 v^2}$