Answer : The mass of 
required are, 35 kg
Explanation :
First we have to calculate the mass of 
.
The first step balanced chemical reaction is:
Molar mass of = 115 g/mole
Molar mass of = 87 g/mole
Let the mass of be, 'x' grams.
From the balanced reaction, we conclude that
As, 
of react to give 
of
So, 
of react to give 
of
And as we are given that the yield produced from the first step is, 65 % that means,
The mass of obtained = 0.4542x g
Now we have to calculate the mass of 
.
The second step balanced chemical reaction is:
Molar mass of = 87 g/mole
Molar mass of = 55 g/mole
From the balanced reaction, we conclude that
As, 
of react to give 
of
So, 
of react to give 
of
And as we are given that the yield produced from the second step is, 80 % that means,
The mass of obtained = 0.2296x g
The given mass of Mn = 8.0 kg = 8000 g (1 kg = 1000 g)
So, 0.2296x = 8000
x = 34843.20 g = 34.84 kg = 35 kg
Therefore, the mass of required are, 35 kg
