Question

Classify the following as elements or compounds Iron, Iron sulphide, Sulphur, Chalk, Washing soda, Sodium, Carbon, Urea

Answer 1

Iron,sulphur,sodium and carbon are elements.

Iron sulphide, chalk, washing soda, urea are compounds.

Explanation:

• We are given a set of compounds  Iron, Iron sulphide, Sulphur, Chalk, Washing soda, Sodium, Carbon, Urea.
• We are asked to classify them as elements and compounds.
• Elements are those compounds which are completely pure in state.Elements are formed from atoms of one kind.
• Compounds are formed from a group of elements or compounds.
• Compounds always have more than one atom.
• From the given subtsance we see that only iron,sulphur,sodium and carbon are in its pure form without combining with other atoms.Hence they are classified as elements.
• On the other hand these substances iron sulphide, chalk, washing soda, urea are compounds which are made up of multiple elements.

Answer 2

Iron, Sulphur, Sodium & Carbon  are elements

Explanation:

• Element is the species having same number of protons in nuclei.

For example - $O_2$ has atomic number of 8, so it has all atoms having 8 protons.

Element: Iron, sulphur, sodium, carbon

Compound - When two elements or more than two gets combined then the resultant is what we call as Compound. It has also been stated that two same elements cannot combine to form a compound.

Example - Na + Cl --> NaCl

Sodium + Chlorine --> Sodium Chloride (Compound)

Compound: iron sulphide, chalk, washing soda, urea