How many hydrogen atoms are present in 0.70 moles of ptcl2 (nh3) 2?

In this case, the hydrogen atoms are present in the (NH3) 2 part of the molecule. The sign (NH3) 2 mean that there are two NH3 molecules in their compound. That means the total atom of hydrogen would be: 3*2 = 6 atom for every compound molecule

Since there is 0.7 mole of compound, then the hydrogen atom would be:

0.7 mole * 6 = 4.2 moles