AP EAPCET 07-Jul-2022 Shift 1 Paper

For hydrogen and hydrogen like atoms
rn=

n2

Z

where, rn is radius of nth orbit of revolution of electron, Z is the atomic number.
For hydrogen atom, Z=1.
Hence, radius of second orbit is r2=

(2)2

1

=4
For helium atom, Z=2.
Hence, radius of fourth orbit is r4=

(4)2

2

=8
∴ Therefore,

r2

r4

=

4

8

=

1

2

⇒1:2