Answer:
So the answer would be 10 moles
Explanation:
1) Start with the molecular formula for water: 
2) If there are 10 moles of water use a mole ratio to calculate the moles of oxygen it would produce.
(This question is... interesting... since they chose an element that is diatomic in free state so It could TECHNICALLY be two answers, moles of O or moles of
)
The mole ratio is 1 moles of
to 1 moles of O. This is because the coefficient for oxygen in water is simple 1, so the ratio is 1:1.
3) that means if 10 moles of water decompose, they decompose into 10 moles of
and 10 moles of O.
Extra:
About what I was saying before about the question being slightly interesting:
10 moles of pure oxygen is produced but free state oxygen exists as
so it could possibly be 10 OR 5! However, notice it says elements. This leads me to believe the answer is 10 (monatomic oxygen) instead of 5 (free state/diatomic oxygen).
I hope this helps!
Answer: Gas
Explanation:
since the gas molecules arent being forcefully bonded together like a solid would be, and liquids tend to have lower kinetic energy than solids
Sulfur Trioxide is the correct name for SO3
2 NH3+ 2 O2 —> 2 NO+ 3 H2O
Diffusion is the process of a substance spreading out to evenly fill its container or environment. Rate of diffusion of a gas is inversely proportional to the molar mass of the gas.

Lighter(lower) the molar mass of the gas , faster will be its rate of diffusion and heavier (higher) the molar mass of the gas , slower will be its rate of diffusion.
We have to arrange the given gases from slowest rate of diffusion to fastest rate of diffusion that means we need to arrange gases from higher molar mass to lower molar mass.
Molar mass of given gases are :
Cl = 35.5 g/mol
Xe = 131.29 g/mol
He = 4.00 g/mol
N = 14.00 g/mol
So correct order for slowest rate of diffusion (highest molar mass) to fastest rate of diffusion (lowest molar mass) is :
Xe , Cl , N , He
Xe having the highest molar mass will have the slowest rate of diffusion and He with lowest molar mass will have the fastest rate of diffusion, so option 'c' is correct.
Note : Slowest rate of diffusion = High Molar Mass
Fastest rate of diffusion = Low Molar Mass