Answer:
7.22 x 10²³molecules
Explanation:
Given parameters:
Number of moles of hydrogen = 1.2moles
Unknown:
Number of molecules of hydrogen = ?
Solution:
From the concept of moles, a mole of a substance contains the Avogadro's number of particles.
1 mole of a substance = 6.02 x 10²³ molecules;
So; 1.2 moles of hydrogen = 1.2 x 6.02 x 10²³ molecules;
= 7.22 x 10²³molecules
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: The rate of appearance of
is 
Explanation:
Rate law says that rate of a reaction is directly proportional to the concentration of the reactants each raised to a stoichiometric coefficient determined experimentally called as order.

The rate in terms of reactants is given as negative as the concentration of reactants is decreasing with time whereas the rate in terms of products is given as positive as the concentration of products is increasing with time.
Rate in terms of disappearance of HBr =
= ![\frac{1d[H_2]}{dt}](https://tex.z-dn.net/?f=%5Cfrac%7B1d%5BH_2%5D%7D%7Bdt%7D)
Rate in terms of appearance of
= ![\frac{1d[Br_2]}{dt}](https://tex.z-dn.net/?f=%5Cfrac%7B1d%5BBr_2%5D%7D%7Bdt%7D)
![-\frac{1d[HBr]}{2dt}=\frac{d[H_2]}{dt}=\frac{d[Br_2]}{dt}](https://tex.z-dn.net/?f=-%5Cfrac%7B1d%5BHBr%5D%7D%7B2dt%7D%3D%5Cfrac%7Bd%5BH_2%5D%7D%7Bdt%7D%3D%5Cfrac%7Bd%5BBr_2%5D%7D%7Bdt%7D)
Given :
![-\frac{1d[HBr]}{dt}=0.140Ms^{-1}](https://tex.z-dn.net/?f=-%5Cfrac%7B1d%5BHBr%5D%7D%7Bdt%7D%3D0.140Ms%5E%7B-1%7D)
The rate of appearance of
;
![\frac{1d[Br_2]}{dt}=-\frac{1d[HBr]}{2dt}=\frac{1}{2}\times 0.140=0.0700Ms^{-1}](https://tex.z-dn.net/?f=%5Cfrac%7B1d%5BBr_2%5D%7D%7Bdt%7D%3D-%5Cfrac%7B1d%5BHBr%5D%7D%7B2dt%7D%3D%5Cfrac%7B1%7D%7B2%7D%5Ctimes%200.140%3D0.0700Ms%5E%7B-1%7D)
Thus rate of appearance of
is 
Chemical properties of matter can only be observed and measured by performing a chemical change.
- Density and boiling are not chemical changes.
- This leaves reactivity and combustion. Reactivity does not need to be observed at STP so the statement is wrong.
Combustion is the best answer.
Answer:
The value of
at 4224 K is 314.23.
Explanation:

Initially
4.97 atm 0
At equilibrium
4.97 - p 2p
At initial stage, the partial pressure of oxygen gas = =4.97 atm
At equilibrium, the partial pressure of oxygen gas = 
So, 4.97 - p = 0.28 atm
p = 4.69 atm
At equilibrium, the partial pressure of O gas = 
The expression of
is given as :


The value of
at 4224 K is 314.23.