Which of the following relationships directly express bohr's concept of hydrogen atom?
(i) `E=hv,`
(ii) `mvr=(nh)/(2pi)`
(iii) `E=mc^(2)`,
(iv) `E_(2)-E_(1)=hv`,
(v) `lamda=(h)/(mv)`.

Explanation

The following two relationships directly express bohr's concept in case of hydrogen atoms:
(ii) mvr `=(nh)/(2pi)` and (iv) `E_(2)-E_(1)=hv`
Relation (ii) states that an electron revolve around the nucleus only in those permitted orbits for which the angular momentum is an integral multiple of `(h)/(2pi)`.
Relation (iv) express the idea that whenever an electron jumps fro one stationary orbit to another, there is either an emission or absorption of energy which is equal to the difference of the energies associated with the two orbits.