Question

define element and compound

Answer 1

Element : robert boyle defined element as any substance that cannot be decomposed into further simple substance by a physical or chemical change 

example: hydrogen.helium etc..,

Compound : a thing that is composed of two or more separate elements; a mixture.
 
example: Nacl,etc..,

Answer 2

element - a particle which cannot be broken into simplier substances physically or chemically is called an element.
ex - oxygen,hydrogen etc..
compound - a combination of 2 or more elements or compounds is called a compound.
ex-
  2H₂+O₂⇒2H₂O

Zn+2HCl⇒ZnCl₂+H₂.