The   partial  pressure of hydrogen is 0.31  atm
calculation
find the number of  hydrogen   moles the container, that is
25/100  x 6.4  =1.6 moles of hydrogen
find the  partial pressure for hydrogen  in 1.6 moles
that is   6.4  moles=  1.24 atm
            1.6  moles= ?
by  cross  multiplication
1.6moles  x1.24  atm/ 6.4 moles=  0.31 atm
        
             
        
        
        
  The initial  mass  of sodium hydroxide  is  3.3 g (answer C)
  <u><em>calculation</em></u>
 Step 1 : find the  moles of iron (ii) hydroxide (  Fe(OH)₂
 moles =  mass÷  molar mass
 from periodic table the  molar mass of Fe(OH)₂  = 56 + [16 +1]2  = 90 g/mol
moles  is therefore = 3.70 g÷ 90 g/mol = 0.041 moles
Step 2:  use the mole ratio to  calculate the moles of  sodium hydroxide (NaOH)
    from given equation  NaOH : Fe(OH)₂    is 2 :1 
therefore the moles of NaOH = 0.041 x 2 = 0.082 moles
Step 3: find  mass of NaOH
mass = moles x molar mass
from the periodic table the  molar mass of NaOH = 23 +16 +1  = 40 g/mol
mass  = 0.082  moles x 40 g/mol = 3.3 g ( answer C)
 
        
             
        
        
        
Answer:
it’s quite simple.
The newton force in a aerodynamic space which could lead to a catastrophic entanglement will be added to the physical quantum molecular structure then subtracted by its opposite, inter dimensional indispensable aerobic activity, then finally multiplied by the sum which was subtracted by the addition to then divide the sum of it all with the solution of the multiplication which would equal to the answer.
        
             
        
        
        
<h2>Natural Abundance for 10B is 19.60%</h2>
Explanation:
- The natural isotopic abundance of 10B is 19.60%.
- The natural isotopic abundance of 11B is 80.40%.
- The isotopic masses of boron are 10.0129 u and 11.009 u respectively.
For calculation of abundance of both the isotopes -
Supposing it was 50/50, the average mass would be 10.5, so to increase the mass we need a more percentage of 11.
Determining it as an equation -
10x + 11y= 10.8
x+y=1 (ratio)
10x + 10y = 10
By taking the denominator away from the numerator
 we get;
y = 0.8
x + y = 1
∴ x = 0.2
To get percentages  we need to multiply it by 100
So, the calculated abundance is 80% for 11 B and 20% 10  B.