Answer is: 60.
In one molecule of C₂₀H₄₂S₃O₂, there is 2 atoms of oxygen (subscript after oxygen indicates number of atoms of oxygen in chemical (molecular) formula).
So, in 30 molecules of C₂₀H₄₂S₃O₂, there is: 30·2 = 60 atoms of oxygen.
From the equation:
1 mole Fe₂O₃ needs 3 moles of CO
1.75 moles require:
1.75 x 3
= 5.25 moles of CO
It is in the center and everything surrounds it
Answer: The 234.74 grams of sample should be ordered.
Explanation:
Let the gram of 114 Ag to ordered be 
The amount required for the beginning of experiment = 0.0575 g
Time requires to ship the sample = 4.2hour = 252 min(1 hr = 60 min)
Half life of the sample =
= 21 min

![\log[N]=\log[N_o]-\frac{\lambda t}{2.303}](https://tex.z-dn.net/?f=%5Clog%5BN%5D%3D%5Clog%5BN_o%5D-%5Cfrac%7B%5Clambda%20t%7D%7B2.303%7D)
![\log[0.0575 g]=\log[N_o]-\frac{0.033 min^{-1}\times 252 min}{2.303}](https://tex.z-dn.net/?f=%5Clog%5B0.0575%20g%5D%3D%5Clog%5BN_o%5D-%5Cfrac%7B0.033%20min%5E%7B-1%7D%5Ctimes%20252%20min%7D%7B2.303%7D)

The 234.74 grams of sample should be ordered.