Answer: KMnO4-
Explanation:
You're looking at one potassium plus a polyatomic ion.
So K plus MnO4, equals:
KMnO4-
It also has a molar mass of 158.04 g/mol, I don't know if you need that, but I thought it would be nice to include it.
When sodium amide i.e.
reacts with water i.e.
results in the formation of sodium hydroxide i.e.
and ammonia
.
The chemical reaction is given by:

Now, when ammonia i.e.
reacts with water results in the formation of ammonium hydroxide i.e. 
The chemical reaction is given by:

Thus, the products of the above reactions are ammonia and ammonium hydroxide (without sodium ion).
The structures of the products are shown in figure (1): ammonium hydroxide and figure (2) ammonia.
The volume of copper : 3.24 ml
<h3>Further explanation
</h3>
Density is a quantity derived from the mass and volume
Density is the ratio of mass per unit volume
With the same mass, the volume of objects that have a high density will be smaller than objects with a smaller type of mass
The unit of density can be expressed in g/cm³ or kg/m³
Density formula:

ρ = density
, g/cm³ or kg/m³
m = mass
, g or kg
v = volume
, cm³ or m³
A common example is the water density of 1 gr / cm³
The density of copper : 8.96 gr/ml
mass of copper : 29 g
then the volume :

Density is defined as mass/volume (or m/v).
So,
(126.0 g)/(12.5 cm^3)= 10.08 g/cm^3
If your teacher requires correct significant figures, the answer is 10.1 g/cm^3.
If not, the first answer is fine.