The first one is D, the second one is A and the last is C and D
Answer: The mass in 
atoms of zinc is 0.405 g.
Explanation:
Given: Atoms of zinc =
It is known that 1 mole of every substance contains 
atoms. So, the number of moles in given number of atoms is as follows.
As moles is the mass of a substance divided by its molar mass. So, mass of zinc (molar mass = 65.39 g/mol) is calculated as follows.
Thus, we can conclude that the mass in atoms of zinc is 0.405 g.
They discovered that *elements* show increase in atomic numbers across the period.
Energy of reactants is higher than the products , I am not sure through
Answer:
Reduction
Explanation:
The oxidation reduction reactions are called redox reaction. These reactions are take place by gaining or losing the electrons and oxidation state of elements are changed.
Oxidation:
Oxidation involve the removal of electrons and oxidation state of atom of an element is increased.
Reduction:
Reduction involve the gain of electron and oxidation number is decreased.
In given reaction fluorine gas gain two electron and form fluoride ions.
F₂(g) + 2e⁻ → 2F⁻(aq)
The given reaction is reduction because oxidation state is decreased from zero to -1.
