$MSO_4×7H_2O$ $= m + 32 + 64 + 126 = m + 222$
તથા $\,\% \,M = \frac{m}{{m +222}} \times 100 = 9.87\,$ (જે આપેલ છે.)
$\therefore \,\,\,100\,m = 9.87\,m\, + \,222\, \times \,9.87\,$
$\,\therefore \,\,\,\,90.13\,m = 222\, \times \,9.87\,\,\,$
$\therefore \,\,m = \frac{{222 \times \,9.87}}{{90.131}} = 24.3$