Question

A chemical reaction in which two or more substances undergo a chemical union to form a more complex substance is a _______ reaction.
A. double replacement
B. substitution
C. decomposition
D. combination

Answer 1

Answer : The correct option is, (D) Combination

Explanation :

• Double replacement reaction : A chemical reaction in which a positive cation and a negative anion of the two reactants exchange places to give two new products or compounds.

        The general representation of this reaction is,

         $AB+CD\rightarrow AD+CB$

         (A and C are the cations, B and D are the anions)

• Substitution reaction : A chemical reaction in which a more reactive element displaces the least reactive element.

        The general representation of this reaction is,

         $A+BC\rightarrow A+CB$

• Decomposition reaction : A chemical reaction in which a bigger compound breaks into two or more smaller compounds or elements.

        The general representation of this reaction is,

         $AB\rightarrow A+B$

• Combination reaction : A chemical reaction in which two or more substances react to form a more complex substance.

        The general representation of this reaction is,

         $A+B\rightarrow AB$

Hence, the correct option is, (D) Combination

Answer 2

Answer:d. Combination