b
આપેલ, \(\pi_1 = 4.92\,atm\) ,  \(\pi_2 = 1.5\,atm\)

\(\,{C_1}\,\, = \,\,\frac{{36}}{{180\,\, \times \,\,1}}\)

\(\left( {\because \,\,C\,\, = \,\,\frac{w}{{m\,\, \times \,\,V}}} \right)\,\,\,{C_2}\,\, = \,\,?\)

\(\pi_1V_1 = n_1S_1T_1\)  અને  \(\pi_2V_2 = n_2ST_2\) સમાન તાપમાનેે,

\(\frac{{{\pi _1}}}{{{\pi _2}}}\,\, = \,\,\frac{{{n_1}}}{{{n_2}}}\,\, \times \,\,\frac{{{V_2}}}{{{V_1}}}\,\, = \,\,\frac{{{C_1}}}{{{C_2}}}\) અથવા  \(\frac{{4.92}}{{1.5}}\,\, = \,\,\frac{{36}}{{180\,\, \times \,\,{C_2}}}\)

\(\therefore \,\,{C_2}\,\, = \,\,0.061\,\,mol/litre\)