Answer:
sunlight is the answer i think
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
Answer:
41.4%
Explanation:
The salt copper II fluoride tetrahydrate is a hydrated salt. A hydrated salt is a salt that has some molecules of water of crystalization attached to its structure. The formula of the salt is CuF2.4H2O
The first step is to calculate the molecular mass of the compound as follows
[64 + 2(19) + 4((2×1) + 16)] = [64 + 38 + 72]= 174gmol-1
Mass of water of crystallization= 4((2×1) + 16) = 72 g
Percentage by mass of water of crystallization= 72 / 174 ×100
Percentage by mass of water if crystalization = 41.4%
I believe the change of state shown in the model is deposition.
Deposition is a process in which gases change phase and turns directly in solids without passing through the liquid phase. It is the opposite of sublimation.
One of the major difference between gases and solids is the distance between molecules; in gases the inter molecular spaces are large, while in solid they are very small, making solids be the most dense, with closely packed molecules. This is evident in the diagram, the phase changed from gases to solids.