Question

Select the correct answer from the choices A, B, C, and D which are given. Write only the letter corresponding to the correct answer.

Which is the correct general form for double displacement reactions?

• A. AB + C ⇢ A + CB
• B. A + B ⇢ AB
• C. AB + CD ⇢ AD + CB
• D. None of the above

Answer 1

The correct option is C

AB + CD ⇢ AD + CB

Explanation for correct option:

Option C

Double decomposition reaction:

• These are the reactions in which two compounds exchange their radicals to form two different compounds.
• A double displacement reaction is a type of reaction in which two reactants exchange ions to form two new compounds.
• Most of the double displacement reactions occur between ionic compounds.

For example:

${\mathrm{AgNO}}_{3\left(\mathrm{aq}\right)}+{\mathrm{NaCl}}_{\left(\mathrm{aq}\right)}\to {\mathrm{AgCl}}_{\left(\mathrm{s}\right)}+{\mathrm{NaNO}}_{3\left(\mathrm{aq}\right)}$

Therefore, option C is correct.

Explanation for incorrect option:

Option A

Simple displacement reaction:

• Displacement reaction is also called substitution reaction.
• These are the reactions involving the displacement of an element from a compound by another element that takes its place.
• The ability of an element to displace another is determined by its relative position in an electrochemical series.

For example:

${\mathrm{Zn}}_{\left(\mathrm{s}\right)}+{\mathrm{CuSO}}_{4\left(\mathrm{aq}\right)}\to {\mathrm{ZnSO}}_{4\left(\mathrm{aq}\right)}+{\mathrm{Cu}}_{\left(\mathrm{s}\right)}$

Therefore, option A is incorrect.

Option B

Synthesis or direct combination reaction:

• When the molecules of two or more substances combine to form molecules of a single substance, the reaction is called a combination reaction.
• Combination reaction is also called synthesis reaction.

For example:

${\mathrm{C}}_{\left(\mathrm{s}\right)}+{\mathrm{O}}_{2\left(\mathrm{g}\right)}\to {\mathrm{CO}}_{2\left(\mathrm{g}\right)}$

Therefore, option B is incorrect.