padi IDC dive theory – Physics

Q4
Underwater it is difficult to determine where a sound comes from because sound travels  _____ times faster in water because water is ___________ than air.
c.) 4 / denser

Q5
A container ship has lost a container which has fallen overboard. It does not float at the surface, nor does it sink to the bottom, it drifts around the water column in mid water. The container is:
a.) Negatively buoyant
b.) Positively buoyant
c.) Neutrally buoyant
d.) Probably buoyant