It is A. Barium
Explanation: I did that already
Einsteinium
I hope that helps
NH4+ and NH3 are an acid-conjugate base pair, since NH4+ is an acid, while NH3 is its conjugate base (since it is without the H+).
H2O and H3O+ can also be considered an acid-conjugate base pair, since H3O+ is an acid, while H2O would be its conjugate base. (But if only 1 answer is to be selected, it should be the NH4+ and NH3)
NH4+ and H3O+ are both acids, and both H2O and NH3 can be considered bases.
The standard ambient temperature and pressure are
Temperature =298 K
Pressure = 1atm
The density of gas is 1.5328 g/L
density = mass of gas per unit volume
the ideal gas equation is
PV = nRT
P = pressure = 1 atm
V = volume
n = moles
R= gas constant = 0.0821 Latm/mol K
T = 298 K
moles = mass / molar mass
so we can write
n/V = density / molar mass
Putting values



Thus molar mass of gas is 37.50g/mol