Your answer is
Ca(OH)₂ + 2HNO₃ → Ca(NO₃)₂ + 2H₂O I hope it is at least :P
To determine the mass, you need to know the molecular weight of the c8h10n4o2 . The molecular weight of <span>c8h10n4o2 would be: 8*12 + 10*1 + 4*14 + 2*16= 194g/mol.
To convert the number of molecules into moles, you need to divide it with 6.02 * 10^23. The calculation of the mass of </span>c8h10n4o2 would be:
(7.20×10^20 molecules) /(6.02 * 10^23 molecule/mol) * 194g/mol= 232 * 10^-3 grams= 0.232 grams
D. I or Iodine
This is because they are both in the same periodic family (the halogens) and thus the number of valence electrons are the same
