Question

Which of the following are not compounds?
(a).Chlorine gas, (b) Potassium chloride, (c) Iron, (d) Iron sulphide, (e) Aluminium, (f) Iodine, (g) Carbon, (h) Carbon monoxide, (i) Sulphur powder

Answer 1

Hint: when some different types of elements combine, they form compounds. The ratio of the elements in the compound is fixed. To make it easier to identify the compound and the element, one can write the formula of the options given above. The options that will consist of more than one type of element will be compound.

Complete answer:
Compounds are chemical substances made up of two or more elements that are chemically bound together in a fixed ratio. It can be said that a compound is the combination of two or more elements. When the elements combine, some individual property of the element is lost and the newly formed compound has new properties. These compounds are represented by chemical formulas.
In the above question, some options are given and we have to tell which among them are not compound. So first we will identify which are the compounds among them. we will write the formulas of all the above options given to identify properly. The formulas are as follows:
(a).Chlorine gas-$\left(C{l}_2\right)$, (b) Potassium chloride-$\left(KCl\right)$, (c) Iron-$\left(Fe\right)$, (d) Iron sulphide-$\left(FeS\right)$, (e) Aluminium-$\left(Al\right)$, (f) Iodine-$\left(I\right)$, (g) Carbon-$\left(C\right)$, (h) Carbon monoxide-$\left(CO\right)$, (i) Sulphur powder-$\left(S\right)$
Among the following options the compounds are (b) Potassium chloride-$\left(KCl\right)$, (d) Iron sulphide-$\left(FeS\right)$ and (h) Carbon monoxide-$\left(CO\right)$
Therefore, the options which are not compounds are- (a) Chlorine gas-$\left(C{l}_2\right)$, (c) Iron-$\left(Fe\right)$, (e) Aluminium-$\left(Al\right)$, (f) Iodine-$\left(I\right)$, (g) Carbon-$\left(C\right)$ and (i) Sulphur powder-$\left(S\right)$.

Note:
Compounds are of four types: ionic, covalent, metallic and coordinate covalent. For forming the compounds the different elements are held together by certain types of bonds. The differences in the types of bonds in compounds differ based on the types of elements present in the compound. A compound can be converted to a different chemical substance by interaction with a second substance via a chemical reaction. In this process, bonds between atoms may be broken in either or both of the interacting substances, and new bonds formed.