Answer:
Only
gives spontaneous reaction.
Explanation:
A redox reaction will be spontaneous if standard reduction potential (
) of the reaction is positive. Because it leads to negative standard gibbs free energy change (
), which is a thermodynamic condition for spontaneity of a reaction.

Where
and
represents standard reduction potential of reduction half cell and standard reduction potential of oxidation half cell.
(1) Oxidation:
; 
Reduction:
; 
So, 
Hence this pair will give spontaneous reaction.
(2) Similarly as above, 
Hence this pair will give non-spontaneous reaction.
(3) Similarly as above, 
Hence this pair will give non-spontaneous reaction.
(4) Similarly as above, 
Hence this pair will give non-spontaneous reaction.
1) 1 molecules
2) 2 oxygen atoms
3)2 moles of Al2O3 are formed
4)4:3
Grams of Ca(NO₃)₂ produced : 0.985 g
<h3>Further explanation</h3>
A reaction coefficient is a number in the chemical formula of a substance involved in the reaction equation. The reaction coefficient is useful for equalizing reagents and products.
Reaction
CaCl₂ + 2AgNO₃ → 2AgCl + Ca(NO₃)₂
MW AgNO₃ : 107.9+14+3.16=169.9
mol AgNO₃ :

mol ratio Ca(NO₃)₂ : AgNO₃ = 1 : 2, so mol Ca(NO₃)₂ :

MW Ca(NO₃)₂ : 40.1+2.14+6.16=164.1 g/mol
mass Ca(NO₃)₂ :

valance electrons that reside in the outermost shell of an atom in the highest energy level. They are important to atoms because the fewer valence electrons that the atom holds, it becomes less stable.
I take honors chemistry I hope this helps.