Answer:
A. Non-metal
B. Six
C. 2
D.NA2O
E.Oxygen
Explanation:
Oxygen is the element in the second period (second horizontal row) and Group VI A of the periodic table. These properties apply to oxygen
The balanced equation is
2Al + 2KOH + 6H2O -----> 2K[Al(OH)4 + 3H2.
From the above we see that 2 moles of K react with 2 moles of Al.
So 2 .94 moles of aluminium will react with 2.94 moles of potassium (answer)
Answer:
Ammonia is the richest source of nitrogen on a mass percentage basis because it has 82.35% of nitrogen by mass.
Explanation:
Percentage of element in compound :

(a) Urea, 
Molar mass of urea = 60 g/mol
Atomic mass of nitrogen = 14 g/mol
Number of nitrogen atoms = 2

(b) Ammonium nitrate, 
Molar mass of ammonium nitrate = 80 g/mol
Atomic mass of nitrogen = 14 g/mol
Number of nitrogen atoms = 2

(c) Nitric oxide, NO
Molar mass of nitric oxide = 30 g/mol
Atomic mass of nitrogen = 14 g/mol
Number of nitrogen atoms = 1

(d) Ammonia, 
Molar mass of ammona = 17 g/mol
Atomic mass of nitrogen = 14 g/mol
Number of nitrogen atoms = 1
Ammonia is the richest source of nitrogen on a mass percentage basis because it has 82.35% of nitrogen by mass.