Which substance reacts with an acid to form hydrogen gas?

Hey guys so i need to know what is _nh3+> nh4oh ~chemistry~

What is the binding energy of a nucleus that has a mass defect of 5.81*10-^29 kg a 5.23*10-^12 j b 3.15* 10^12 j c 1.57*10-3 j d 9.44*10^20 j

Mercury metal is poured into a graduated cylinder that holds exactly 22.5 ml the mercury used to fill the cylinder mass in 306.0 g from this information calculate the density of mercury