Question

An unknown substance' A 'is on thermal decomposition produces 'B 'and 'C'.what is 'A' ? An element, a compound or a mixture.

Answer 1

Since A decomposes it cant b an element bcuz elements cant break down.
if it were a mixture the term 'thermal decomposition' would not b used...bcuz it is states a chemical change.
so A has to be a compound.

Answer 2

A cannot be an element because elements cannot be broken down into anything simpler than it already is.It cannot be a mixture because thermal decomposition is used to break the chemical bonds of substances.Mixtures are not chemically bonded.Simple physical methods are enough to separate them.Therefore A is a compound.