Question

What term best describes the type of reaction that happens when a single element reacts with a molecule or compound, producing a new single element and a new molecule or compound?
A. an isolation reaction

B. a single combustion reaction

C. a single replacement reaction

D. a double replacement reaction

Answer 1

Answer: a single replacement reaction

Explanation:

Combustion is a type of chemical reaction in which fuel is reacted with oxygen to form carbon dioxide and water.

Example:  

$C_6H_{12}O_6+O_2 \rightarrow CO_2+H_2O$

Double displacement reaction is one in which exchange of ions take place.  

Example: $2NaOH(aq)+(NH_4)_2SO_4(aq)\rightarrow 2NH_4OH(aq)+Na_2SO_4(aq)$

Single replacement reaction is a chemical reaction in which more reactive element displaces the less reactive element from its salt solution.

Example: $Zn+CuCl_2\rightarrow ZnCl_2+Cu$

Here Zinc an element reacts with the compound copper chloride  to form new compound zinc chloride and new element copper.

Answer 2

The answer is

C. A single replacement reaction (acid reactions)

An example would be the reaction between simple metal Potassium (K) and Water (H2O), resulting in a much solid compound called Potassium Hydroxide (KOH) and hydrogen gas is set free.

K+H2O --> KOH