Assertion (A): Bohr claims that the electron's angular momentum is quantized as it orbits the nucleus.

Reason (R): Each electron engages in interaction NOT just with the positively charged nucleus but also with every other electron.

Both A and R are true but R is NOT the correct explanation of A.

The de Broglie hypothesis offered an explanation for the quantization of the orbiting electron's angular momentum. The wave aspect of the electron is what causes the quantized electron orbits and energy levels, and only resonant standing waves can last. The following figure clearly depicts the standing wave and its quantization.