A line. You can even check a map
<span>MicroR Meter, with Sodium Iodide Detector
<span>Geiger Counter, with Geiger-Mueller (GM) Tube or Probe
<span>Portable Multichannel Analyzer</span>
</span>
</span>
answer: focus or hypocenter
enplanation: when energy release at the focus, seismic waves travel outward from that point in all directions.
The gas flows from higher concentration/pressure to lower concentration/pressure, which is outside the ball.
I believe the answer is C. The bonds in the compound magnesium sulfate is ionic and covalent. Magnesium sulfate is soluble in water. When the said compound is dissolved in water, it dissociates into magnesium ions and sulfate ions. However, the bonds that held together the sulfate ions is covalent.