b
\(\frac{{{{\left( {{t_{\frac{1}{2}}}} \right)}_1}}}{{{{\left( {{t_{\frac{1}{2}}}} \right)}_2}}}{\mkern 1mu} {\mkern 1mu}  = {\mkern 1mu} {\mkern 1mu} {\left( {\frac{{{a_2}}}{{{a_1}}}} \right)^{n{\kern 1pt}  - {\kern 1pt} 1}}\)

\({\mkern 1mu} {\mkern 1mu}  \Rightarrow {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \frac{{{t_{\frac{1}{2}}}}}{{\frac{{{t_{\frac{1}{2}}}}}{2}}}{\mkern 1mu} {\mkern 1mu} {\mkern 1mu}  = {\mkern 1mu} {\mkern 1mu} {\left( {\frac{{2a}}{a}} \right)^{n - 1}}\)

\(2\,\, = \,\,(2){\,^{n - 1}}\, \Rightarrow \,\,n\,\, - \,\,1\,\, = \,\,1\,\,\, \Rightarrow \,\,\,n\,\, = \,\,2\)

તેથી પ્રક્રિયાનો ક્રમ \( 2\) છે .