The mineral that is the hardest known substance in nature is a diamond.
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Protons, the number of protons cannot change or the element will change as well.
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:
b) The boiling point of the solution is always greater than the boiling point of the pure solvent.
Explanation:
Hello,
In this case, when we add a nonvolatile solute to a volatile solvent which has a relatively low boiling point, we can evidence the increase of the boiling point of the resulting solution as more energy must be supplied to take the molecules from liquid to gas. This fact matches with the boiling point elevation colligative property due to the solute's addition, which states that the boiling point of the solution is always greater than the boiling point of the pure solvent, therefore, answer is b).
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