Answer:
B. Cl.
Explanation:
These are Group 7 elements whose reactivity reduces as you go down the group. Chlorine has a smaller atoms than the rest and has a stronger tendency to grab an electron in its valency shell. This is because its nucleus is closer to the outer electrons than the other elements.
The correct amount of force i believe is
f= 40 newton
i got the answer by using the formula below
force = mass x acceleration
f=5kg *8.0 m/s^2
Workings are in the picture! first you get moles of Fe2O3, then you get moles of Al and then you get mass of Al!