We need (i) the stoichiometric equation, and (ii) the equivalent mass of dihydrogen.
Explanation:
1
2
N
2
(
g
)
+
3
2
H
2
(
g
)
→
N
H
3
(
g
)
11.27
g
of ammonia represents
11.27
⋅
g
17.03
⋅
g
⋅
m
o
l
−
1
=
?
?
m
o
l
.
Whatever this molar quantity is, it is clear from the stoichiometry of the reaction that 3/2 equiv of dihydrogen gas were required. How much dinitrogen gas was required?
Potassium is placed where it is based on its properties and it's reactivity. It's also placed there based on it's atomic number.
The answer would be Gravity.