Question

4. Which of the occurs in combined sate in earth's crust? *
Oxides
Caebonates
Sulphates
All of these​

Answer 1

The elements which are reactive and have a tendency to combine with oxygen or air, moisture, carbon dioxide and non-metals like carbon, nitrogen, sulphur, phosphorus, arsenic, halogen, etc. occur in the combined state. These elements occur in the crust of the earth in the form of their compounds.