I might go with d it seems right to me hope this helps.
Given :
2NOBr(g) - -> 2NO(g) + Br2(g)
Initial pressure of NOBr , 1 atm .
At equilibrium, the partial pressure of NOBr is 0.82 atm.
To Find :
The equilibrium constant for the reaction .
Solution :
2NOBr(g) - -> 2NO(g) + Br2(g)
t=0 s 1 atm 0 0
1( 1-2x) 2x x
So ,

At equilibrium :
![K_{eq}=\dfrac{[NO]^2[br_2]}{[NOBr]^2}\\\\K_{eq}=\dfrac{0.18^2\times 0.9}{0.82^2}\\\\K_{eq}=0.043\ atm](https://tex.z-dn.net/?f=K_%7Beq%7D%3D%5Cdfrac%7B%5BNO%5D%5E2%5Bbr_2%5D%7D%7B%5BNOBr%5D%5E2%7D%5C%5C%5C%5CK_%7Beq%7D%3D%5Cdfrac%7B0.18%5E2%5Ctimes%200.9%7D%7B0.82%5E2%7D%5C%5C%5C%5CK_%7Beq%7D%3D0.043%5C%20atm)
Hence , this is the required solution .
A free-radical substitution reaction is likely to be responsible for the observations. The reaction mechanism of a reaction like this can be grouped into three phases:
- Initiation; the "light" on the mixture deliver sufficient amount of energy such that the halogen molecules undergo homologous fission. It typically takes ultraviolet radiation to initiate fissions of the bonds.
- Propagation; free radicals react with molecules to produce new free radicals and molecules.
- Termination; two free radicals combine and form covalent bonds to produce stable molecules. Note that it is possible for two carbon-containing free-radicals to combine, leading to the production of trace amounts of long carbon chains in the product.
Initiation

where the big black dot indicates unpaired electrons attached to the atom.
Propagation






Termination

<u>Answer:</u> The isotopic symbol of barium is
and that of strontium is 
<u>Explanation:</u>
Nuclear fission reactions are defined as the reactions in which a heavier nuclei breaks down in two or more smaller nuclei.
In a nuclear reaction, the total mass and total atomic number remains the same.
- For the given fission reaction:

Total mass on reactant side = total mass on product side
235 + 1 = A + 94 + 3
A = 139
Total atomic number on reactant side = total atomic number on product side
92 + 0 = Z + 36 + 0
Z = 56
The isotopic symbol of barium is 
- For the given fission reaction:

Total mass on reactant side = total mass on product side
235 + 1 = A + 143 + 3
A = 90
Total atomic number on reactant side = total atomic number on product side
92 + 0 = Z + 54 + 0
Z = 38
The isotopic symbol of strontium is 
Hence, the isotopic symbol of barium is
and that of strontium is 
The radioactive isotope's atomic number decreases by two, and the alpha particle has an atomic number of 2. It wasnt clear which one you were asking for, so there is both.