The number density of molecules of a gas depends on their distance r from the origin as, n(r)=. Then the total number of molecules is proportional to
a) 

b) 

c) 

d) 

The number density of molecules of a gas depends on their distance r from the origin as, n(r)=. Then the total number of molecules is proportional to
a) 

b) 

c) 

d) 

n =
⇒ =dr
⇒ N = 4
Put r^{2} = t
2r dr = dt
N =
=dt
N