Which of the following statements are true regarding Bohr's model of hydrogen atom
(I) Orbiting speed of electron decreases as it shifts to discrete orbits away from the nucleus
(II) Radii of allowed orbits of electron are proportional to the principal quantum number
(III) Frequency with which electrons orbits around the nucleus in discrete orbits is inversely proportional to the principal quantum number
(IV) Binding force with which the electron is bound to the nucleus increases as it shifts to outer orbits
Select correct answer using the codes given below Codes :
(a) I and III
(b) II and IV
(c) I, II and III
(d) II, III and IV
Answers
Answer:
(a) I and III is the correct answer.
Explanation:
To find :
true statement regarding Bohr's model of hydrogen atom =?
Bohr in his model of hydrogen atom stated that electrons revolve in different orbits around the nucleus.
To check the correct option will we see all the given options.
(I) Orbiting speed of electron decreases as it shifts to discrete orbits away from the nucleus.
Actually, the velocity of electron increase with increase in atomic number.
The speed of electron in hydrogen atom is the orbital speed of electron.
It is given by v= 2.18*10^6/n m/s.
Thus,v is indirectly promotional to n.
Thus when n will increase v will decrease.
Hence, it is a correct statement.
(II) Radii of allowed orbits of electron are proportional to the principal quantum number.
In a hydrogen atom, the radius of orbit is given by the formula
r = 0.529 n^2
Thus r is directly proportional to n^2.
Hence it is an incorrect statement.
(III) Frequency with which electrons orbits around the nucleus in discrete orbits is inversely proportional to the principal quantum number.
Frequency of electron is given by the formula
f= 6.56*10^15/n^3
Thus frequency is inversely proportional to n.
Hence, it is correct statement.
(IV) Binding force with which the electron is bound to the nucleus increases as it shifts to outer orbits.
The energy will always decarese when electron shift to outer orbits.
This is hence incorrect statement.
Hence, (a) I and III is the correct answer.