When you drop an iron ball in mercury it will float.
The iron ball will float in mercury when you drop the iron ball in the mercury because the density of iron ball is lesser than the density of mercury so the upthrust force acting on the solid ball is greater than the weight of the solid ball which results to float the solid ball.
A piece of iron is denser than water so it will sink in the water as no amount of buoyant force will be able to balance the weight of the piece of iron, however when placed in mercury, mercury being denser than the iron piece, the iron piece will float in mercury.
Because mercury's density is very high, objects that you might consider heavy, such as lead weights or a steel ball bearing, will float in it.
The chemical symbol for Mercury is Hg. Mercury was named after the Roman god.
Its chemical symbol (Hg) comes from hydrargyrum from the Greek word hydrargyros meaning 'water' and 'silver'.
Mercury is a naturally-occurring chemical element found in rock in the earth's crust, including in deposits of coal.
On the periodic table, it has the symbol "Hg" and its atomic number is 80.
Mercury is used in many scientific instruments such as thermometers and barometers.
Due to its electrical conductivity it is used to make silent switches, while its vapor form makes it useful in streetlights and fluorescent lamps.
Mercury is the only metal that is a liquid at standard temperature and pressure.
The only other liquid element under standard conditions is bromine (a halogen), although the metals rubidium, cesium, and gallium melt at a temperature just above room temperature.
Mercury is a very rare element in the Earth's crust.