Question

Which of the following are not compound chlorine gas , potassium chloride , iron powder , iron sulphide ,aluminium foil, iodine vapour, graphite, carbon monoxide, sulphur powder , diamond

Answer 1

Chlorine gas, Iron Powder, Aluminium foil, Iodine vapour, graphite and diamond are not compounds. These are different states of an element.
ie., Cl₂, Fe, Al, I₂ and C atoms' allotropes.

Answer 2

Answer: chlorine gas, iron powder, aluminium foil, iodine vapor, graphite, sulfur powder and diamond

Explanation:

Element is a pure substance which is composed of atoms of similar elements.

Thus chlorine gas $(Cl_2)$ which consists of only chlorine atoms, iron powder $(Fe)$ which consists of only iron atoms,  aluminium foil $(Al)$  which consists of only aluminium atoms, iodine vapor $(I_2)$ which consists of only iodine atoms, graphite $C(s)$ which consists of only carbon atoms , sulfur powder $(S_8)$ which consists of only sulfur atoms and diamond $(C)$ which consists of only carbon atoms are all examples of elements.

Compound is a pure substance which is made from atoms of different elements chemically combined together in a fixed ratio by mass.

Thus potassium chloride $(KCl)$ which consists of potassium and chlorine atoms, iron sulphide $(FeS)$ which consists of iron and sulfur atoms, and carbon monoxide $(CO)$ which consists of carbon and oxygen atoms combined in fixed proportion by mass are all examples of compounds.