question_answer

Radius of first Bohr orbit is r. What is the radius of second Bohr orbit?

A)  8r                                          

B)  2r

C)   4r                                         

D)  \[2\sqrt{2}r\]

Correct Answer: C

Solution :

 From Bohr's theory of atom, we have if e, m be the charge and mass of electron, Z be the atomic number, then radius of nth Bohr orbit is                 \[r={{n}^{2}}\frac{{{h}^{2}}{{\varepsilon }_{o}}}{\pi mZ{{e}^{z}}}\] \[\Rightarrow \]               \[r={{n}^{2}}\] For         \[n=2\] \[{{r}_{2}}={{(2)}^{2}}r=4r\]