The weight is 132.15 g.
The molar mass of NH42 SO4 = 152.40278 g/mol
132.15 amu
To find the number of moles of hydrogen in 3.5 moles of (NH4)2CO3, first identify the stoichiometry of the compound. In (NH4)2CO3, there are two moles of hydrogen per mole of compound. Therefore, in 3.5 moles of (NH4)2CO3, there would be 2 * 3.5 = 7 moles of hydrogen.