A container of helium is at 40°C with a volume of 2.55 L. What must the temperature be (in °C) raised to for the volume to be 4.50 L?

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

Many ionic compounds and a few highly polar covalent compounds are because they completely ionize in water to create a solution filled with charged ions that can conduct an electric current.

How might this scientific phenomena be explained? a paper clip floats on water.