Q. Let A* _{n}* be the area enclosed by the nth orbit in a hydrogen atom. The graph of

**against**

*ln*(A_{n}/A_{1})

*In*(*n*)(a) will not pass through origin

(b) will be a straight line with slope 4

(c) will be a rectangular hyperbola

(d) will be a parabola

**Ans: (b)**

Sol: A_{n} = π r_{n}^{2}

A_{n} = π(r_{0}n^{2})^{2}

Hence , A_{n} = πr_{0}^{2}n^{4} = A_{1}r^{4}

A_{n}/A_{1} = n^{4}

Taking log ,

ln(A_{n}/A_{1}) = 4ln(n)

Hence Straight line with slope 4 .