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.

Zinc + Hydrochloric acid ⇢ Zinc chloride + Hydrogen

($\mathrm{Zn}+2\mathrm{HCl}\to {\mathrm{ZnCl}}_2+{\mathrm{H}}_2$) is an example of:

• A. Double decomposition
• B. Simple displacement reaction
• C. Synthesis or direct combination reaction
• D. Decomposition reaction

Answer 1

The correct option is B

Simple displacement reaction

Explanation for correct option:

Option B

Simple displacement reaction:

• A displacement reaction is also called a 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 a reactivity series.

For example:

$\mathrm{Zn}\left(\mathrm{s}\right)+2{\mathrm{HCl}}_{\left(\mathrm{l}\right)}\to {\mathrm{ZnCl}}_{2\left(\mathrm{aq}\right)}+{\mathrm{H}}_{2\left(\mathrm{g}\right)}$

Therefore, option B is correct.

Explanation for incorrect option:

Option A

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 A is incorrect.

Option C

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.
• A combination reaction is also called a 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 C is incorrect.

Option D

Decomposition reaction:

• When the molecules of one substance split into two or simpler substances, the reaction is called a decomposition reaction.
• These reactions are brought about in the presence of an external agent such as heat, light, and electricity.

For example:

$2{\mathrm{KClO}}_{3\left(\mathrm{s}\right)}\stackrel{∆}{\to }2{\mathrm{KCl}}_{\left(\mathrm{s}\right)}+3{\mathrm{O}}_{2\left(\mathrm{g}\right)}$

Therefore, option D is incorrect.