The two half-reactions are...
Ag→Ag+
and...
NO3→NO
Let's start by balancing the first half-reaction...
Ag→Ag+
The amounts are already balanced; 1:1. The oxygens are balanced. So all that's left is to balance the charge...
Ag→Ag++e−
Now let's do the other equation... Amounts of nitrogen are balanced, so we first need to balance the oxygens...
NO3→NO
4H++NO3→NO+2H2O
Next, we need to balance charge...
4e−+4H++NO3→NO+2H2O
Now let's go ahead and rewrite each half-reaction after being balanced by themselves...
Ag→Ag++e−
4e−+4H++NO3→NO+2H2O
Now we need to multiply by some factor to get the electrons to cancel out. In this case, that factor is 4, which needs to be applied to the top half-reaction...
4(Ag→Ag++e−)=4Ag→4Ag++4e−
Then we combine this half-reaction with the second one above to get...
4Ag+4H++NO3→4Ag++NO+2H2O
Particles that are close together and locked in a place means its
a solid
_Mg + _HCL = _MgCl2 + H2
Separate the terms on each side:
_Mg + _HCl = _MgCl2 + H2
Mg- 1 Mg-1
H-1 H-2
Cl-1 Cl-2
Mg is balanced on both sides so move on to the next (put a 1 in the space).
1Mg
There are two H's and two Cl's on the results side, so to balance the equation put a 2 as a coefficient for HCl and it'll all balance out.
2HCl
Balamced equation will be:
1Mg + 2HCL = 1MgCl2 + H2
The answer is b, because all of the other compounds are covelent
So you have evidence that the experiment is true or correct.