Question

What is the synthesis? What kind of chemical reaction is synthesis? Support your answer with an example.

Answer 1

A reaction in which two or more substances combine together to form a single substance is called a synthesis or combination reaction.
$A$ + $B$ $\to$ $AB$

In the above reaction, substances A and B combine to give a molecule of a new substance, AB.
Carbon burns in oxygen to form a gaseous compound, carbon dioxide.

$C$ + $O_2$$\to$ $C{O}_2$