I would say you are correct so b 4.6
Answer:
<h2><u>Reason:</u></h2>
Catalyst is used as a very fine powder and larger pieces of iron are not used. This is because the surface area of catalyst needs to be large so that more of the surface is exposed to the substrate and more of the substrate is catalyzed.
<h2><u>Important Info:</u></h2>
=> Larger Pieces of Iron has a smaller surface area than the fine particles.
=> Larger the surface area of catalysts/enzymes , more will be the reaction rate and vice versa.
Hope this helped!
<h2>~AnonymousHelper1807</h2>
Answer:
a)CN=12
b)APF=74 %
c)a=0.35 nm
d)ρ=9090.9 
Explanation:
Given that
Nickel have FCC structure
We know that in FCC structure ,in FCC 8 atoms at corner with 1/8 th part in one unit cell and 6 atoms at faces with 1/2 part in one unit cell .
Z=8 x 1/8 + 1/2 x 6 =4
Z=4
Coordination number (CN)
The number of atoms which touch the second atoms is known as coordination number.In other word the number of nearest atoms.
CN=12
Coordination number of FCC structure is 12.These 12 atoms are 4 atoms at the at corner ,4 atoms at 4 faces and 4 atoms of next unit cell.
APF

We know that for FCC

Now by putting the values

APF=0.74
APF=74 %


a=0.35 nm
Density

We know that M for Ni
M=58.69 g/mol
a=0.35 nm


ρ=9090.9 
This is a incomplete question.The complete question is:
A chemist adds 180.0 ml of a 1.77 mol/L of sodium thiosulfate solution to a reaction flask. Calculate the mass in grams of sodium thiosulfate the chemist has added to the flask. Be sure your answer has the correct number of significant digits.
Answer: 50.4 g
Explanation:
To calculate the number of moles for given molarity, we use the equation:
.....(1)
Molarity of sodium thiosulfate solution = 1.77 M
Volume of sodium thiosulfate solution = 180.0 mL = 0.1800 L
Putting values in equation 1, we get:

Mass of sodium thiosulfate =
Thus 50.4 g of sodium thiosulfate the chemist has added to the flask.