I’m assuming you mean ##”weight of”##, instead of ##”water of”##, right? Here’s how I think the data actually looks like:
The weight of the crucible is ##”10.0 g”##. The weight of the crucible + the weight of the copper (II) sulfate pentahydrate is ##”14.98 g”##. Automatically, you know how much copper (II) sulfate pentahydrate you have
##m_(“hydrate”) = “14.98 g” – “10.00 g” = “4.980 g”##
The weight of the crucible + the weight of the residue is ##”13.54 g”##. The “residue” actually represents the anhydrated ##”CuSO”_4##, which means that you now know how much water has been evaporated
##m_(“water”) = m_(“hydrate”) – “(13.54 g – 10.00 g)” = “4.980 g” – “3.540 g”##
##m_(“water”) = “1.440 g”##
You know that water has a molar mass of ##”18.0 g/mol”##. This will help you find the number of you have
##”1.440 g” * (“1 mole”)/(“18.0 g”) = 0.0800## ##”moles”##
The number of molecules is
##”0.0800 moles” * (6.022 * 10^(23) “molecules”)/(“1 mole”) = 4.82 * 10^(22)## ##”molecules”##