Question

What are the metals which exist liquid at room temperature?

Answer 1

Hint: It is a heavy liquid metal which is highly toxic. It was used mostly in batteries, in thermometers, barometers, and in fluorescent lights. The other metal is a soft, silvery metal that rapidly tarnishes in air and reacts with water.

Complete answer:
mercury. It is used in the chemical industry as catalysts and even used for some electrical switches and rectifiers. Previously it was used to manufacture sodium hydroxide and chlorine by electrolysis of brine. Even mercury amalgams were used to do dental fillings. Biological role: mercury has no known role in biology. But at present every mouthful of food we eat contains a little mercury. If doses bigger than $0.1mg$ will be taken, it becomes toxic and one form of mercury, particularly methylmercury, is highly dangerous.
Talking about barium, it is not an extensively used element. Most Is used in drilling fluids for oil and gas wells. It is also used in paints and in glassmaking. Even this does not have any role in biology, however barium sulphate has been found in one particular type of algae. This barium sulphate is insoluble and so can be safely swallowed. It is also given to patients suffering from digestive disorders.
 mercury and barium exist as liquid at room temperature.

Note:
Barium occurs only in combination with other elements. The major ores are barite and witherite. Barium metal can be prepared by electrolysis of molten barium chloride, or by heating barium oxide with aluminium powder.