Here are the names of some substances: Sulphur, copper, oxygen, iron, water, magnesium, mercury Which substance: Is at gas room temperature? Is a liquid metal? Is a solid non-metal? is a chemical compound?

It is highly reactive non-metal and third most abundant element in the universe after hydrogen and helium. Diatomic oxygen(O₂) constitutes 20.8% of earth atmosphere that used in respiration in living organisms.

Mercury(Hg): atomic no.-80

It is shiny, silvery and only metal which is found in liquid state at normal room temperature. Most common use of mercury is in thermometer, barometer, sphygmomanometer etc.

Sulphur(S): atomic no.-16

It is bright yellow crystalline solid non-metal at room temperature in elemental form. Combined sulphur exists in sulphates and sulphides i.e. CaSO₄.2H₂o, MgSO₄.7H₂O, PbS, ZnS etc. Abundance in earth crust is only 0.03-0.1%.

Copper(Co): atomic no.-29

It is pinkish-orange, malleable and ductile metal found in solid state at room temperature. It is commonly used in making wire, alloy etc.

Water(H₂O):

Water covers 71% of earth surface. A molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. It is crucial for all forms of life.