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The correct answer in here is: Limited the burning of soft coal. Some reasons for that are that when Britain was the workshop of the world its coal consumption increased from around 10 million tons per annum in 1800 to almost 200 million tons in 1950 and also that <span>Coal smoke was linked to very high death rates from respiratory diseases such as bronchitis, killing between 800,000 and 1.4 million people in the period 1840-1900.</span>
Answer:
The mole fractions:




Explanation:
The reaction described is:

The limiting reactant is the HBr (oxygen is in excess).
a) The mass (in moles) balance for this sistem:
(the 0.78 is because of the fractional conversion)

(the 1.25 is because of the oxygen excess)
There is only one degree of freedom in this sistem, you can either deffine the moles of HBr you have or the moles of Br2 you want to produce. The other variables are all linked by the equations above.
b) Base of calculation 100 mol of HBr:




The mole fractions:



