Answer:
Density, d = 1.779 g/cm³
Explanation:
The density of a material is given by its mass per unit volume.
Here, height of a piece of magnesium cylinder, h = 5.62 cm
Its diameter, d = 1.34 cm
Radius = 0.67 cm
Volume of he cylinder,


So, the density of the sample is 1.779 g/cm³.
It's A. volume
Pressure =

with const depends on the chosen unit of volume
I think so...
Energy increases with increasing frequency.